If a name does not resolve to anything then it resolves to itself

The new gg format is based on a BNF file which can be found in the `gg`
directory. The code for decoding `.gg` files has been refactored to
mirror that file. The result is more resilient parsing, better errors,
and a greater ability to extend the format in the future.

The new decoder is notable in that it does not use a lexer. Both lexing
and parsing are done in a single step.

The format syntax itself has also been modified. Rather than using
semi-colons everywhere, commas are used as separators in tuples.
Additionally the final comma/semi-colon is no longer required.

BUILD

@@ -1,5 +0,0 @@
-RELEASE=RELEASE_381 # this may have to be changed based on llvm version
-svn co https://llvm.org/svn/llvm-project/llvm/tags/$RELEASE/final $GOPATH/src/llvm.org/llvm
-cd $GOPATH/src/llvm.org/llvm/bindings/go
-./build.sh
-go install llvm.org/llvm/bindings/go/llvm

NOTES

@@ -1,431 +0,0 @@
-Been thinking about the stack and heap a lot. It would be possible, though
-possibly painful, to enforce a language with no global heap. The question really
-is: what are the principles which give reason to do so? What are the principles
-of this language, period? The principles are different than the use-cases. They
-don't need to be logically rigorous (at first anyway).
-
-##########
-
-I need to prioritize the future of this project a bit more. I've been thinking
-I'm going to figure this thing out at this level, but I shouldn't even be
-working here without a higher level view.
-
-I can't finish this project without financial help. I don't think I can get a v0
-up without financial help. What this means at minimum, no matter what, I'm going
-to have to:
-
-- Develop a full concept of the language that can get it to where I want to go
-    - Figure out where I want it to go
-- Write the concept into a manifesto of the language
-- Write the concept into a proposal for course of action to take in developing
-  the language further
-
-I'm unsure about what this language actually is, or is actually going to look
-like, but I'm sure of those things. So those are the lowest hanging fruit, and I
-should start working on them pronto. It's likely I'll need to experiment with
-some ideas which will require coding, and maybe even some big ideas, but those
-should all be done under the auspices of developing the concepts of the
-language, and not the compiler of the language itself.
-
-#########
-
-Elemental types:
-
-* Tuples
-* Arrays
-* Integers
-
-#########
-
-Been doing thinking and research on ginger's elemental types and what their
-properties should be. Ran into roadblock where I was asking myself these
-questions:
-
-* Can I do this without atoms?
-* What are different ways atoms can be encoded?
-* Can I define language types (elementals) without defining an encoding for
-  them?
-
-I also came up with two new possible types:
-
-* Stream, effectively an interface which produces discreet packets (each has a
-  length), where the production of one packet indicates the size of the next one
-  at the same time.
-* Tagged, sort of like a stream, effectively a type which says "We don't know
-  what this will be at compile-time, but we know it will be prefixed with some
-  kind of tag indicating its type and size.
-    * Maybe only the size is important
-    * Maybe precludes user defined types that aren't composites of the
-      elementals? Maybe that's ok?
-
-Ran into this:
-https://www.ps.uni-saarland.de/~duchier/python/continuations.htm://www.ps.uni-saarland.de/~duchier/python/continuations.html
-https://en.wikipedia.org/wiki/Continuation#First-class_continuations
-
-which is interesting. A lot of my problems now are derived from stack-based
-systems and their need for knowing the size input and output data, continuations
-seem to be an alternative system?
-
-I found this:
-
-http://lambda-the-ultimate.org/node/4512
-
-I don't understand any of it, I should definitely learn feather
-
-I should finish reading this:
-http://www.blackhat.com/presentations/bh-usa-07/Ferguson/Whitepaper/bh-usa-07-ferguson-WP.pdf
-
-#########
-
-Ok, so I'm back at this for the first time in a while, and I've got a good thing
-going. The vm package is working out well, Using tuples and atoms as the basis
-of a language is pretty effective (thanks erlang!). I've got basic variable
-assignment working as well. No functions yet. Here's the things I still need to
-figure out or implement:
-
-* lang
-    * constant size arrays
-        * using them for a "do" macro
-    * figure out constant, string, int, etc... look at what erlang's actual
-      primitive types are for a hint
-    * figure out all needed macros for creating and working with lang types
-* vm
-    * figure out the differentiation between compiler macros and runtime calls
-        * probably separate the two into two separate call systems
-    * the current use of varCtx is still pretty ugly, the do macro might help
-      clean it up
-* functions
-    * are they a primitive? I guess so....
-    * declaration and type
-    * variable deconstruction
-    * scoping/closures
-* compiler macros, need vm's Run to output a lang.Term
-* need to learn about linking
-    * figure out how to include llvm library in compiled binary and make it
-      callable. runtime macros will come from this
-    * linking in of other ginger code? or how to import in general
-* comiler, a general purpose binary for taking ginger code and turning it
-  into machine code using the vm package
-    * swappable syntax, including syntax-dependent macros
-* close the loop?
-
-############
-
-I really want contexts to work. They _feel_ right, as far as abstractions go.
-And they're clean, if I can work out the details.
-
-Just had a stupid idea, might as well write it down though.
-
-Similar to how the DNA and RNA in our cells work, each Context is created with
-some starting set of data on it. This will be the initial protein block. Based
-on the data there some set of Statements (the RNA) will "latch" on and do
-whatever work they're programmed to do. That work could include making new
-Contexts and "releasing" them into the ether, where they would get latched onto
-(or not).
-
-There's so many problems with this idea, it's not even a little viable. But here
-goes:
-
-* Order of execution becomes super duper fuzzy. It would be really difficult to
-  think about how your program is actually going to work.
-
-* Having Statement sets just latch onto Contexts is super janky. They would get
-  registered I guess, and it would be pretty straightforward to differentiate
-  one Context from another, but what about conflicts? If two Statements want to
-  latch onto the same Context then what? If we wanted to keep the metaphor one
-  would just get randomly chosen over the other, but obviously that's insane.
-
-############
-
-I explained some of this to ibrahim already, but I might as well get it all
-down, cause I've expanded on it a bit since.
-
-Basically, ops (functions) are fucking everything up. The biggest reason for
-this is that they are really really hard to implement without a type annotation
-system. The previous big braindump is about that, but basically I can't figure
-out a way that feels clean and good enough to be called a "solution" to type
-inference. I really don't want to have to add type annotations just to support
-functions, at least not until I explore all of my options.
-
-The only other option I've come up with so far is the context thing. It's nice
-because it covers a lot of ground without adding a lot of complexity. Really the
-biggest problem with it is it doesn't allow for creating new things which look
-like operations. Instead, everything is done with the %do operator, which feels
-janky.
-
-One solution I just thought of is to get rid of the %do operator and simply make
-it so that a list of Statements can be used as the operator in another
-Statement. This would _probably_ allow for everything that I want to do. One
-outstanding problem I'm facing is figuring out if all Statements should take a
-Context or not.
-
-* If they did it would be a lot more explicit what's going on. There wouldn't be
-  an ethereal "this context" that would need to be managed and thought about. It
-  would also make things like using a set of Statements as an operator a lot
-  more straightforward, since without Contexts in the Statement it'll be weird
-  to "do" a set of Statements in another Context.
-
-* On the other hand, it's quite a bit more boilerplate. For the most part most
-  Statements are going to want to be run in "this" context. Also this wouldn't
-  really decrease the number of necessary macros, since one would still be
-  needed in order to retrieve the "root" Context.
-
-* One option would be for a Statement's Context to be optional. I don't really
-  like this option, it makes a very fundamental datatype (a Statement) a bit
-  fuzzier.
-
-* Another thing to think about is that I might just rethink how %bind works so
-  that it doesn't operate on an ethereal "this" Context. %ctxbind is one attempt
-  at this, but there's probably other ways.
-
-* One issue I just thought of with having a set of Statements be used as an
-  operator is that the argument to that Statement becomes.... weird. What even
-  is it? Something the set of Statements can access somehow? Then we still need
-  something like the %in operator.
-
-Let me backtrack a bit. What's the actual problem? The actual thing I'm
-struggling with is allowing for code re-use, specifically pure functions. I
-don't think there's any way anyone could argue that pure functions are not an
-effective building block in all of programming, so I think I can make that my
-statement of faith: pure functions are good and worthwhile, impure functions
-are.... fine.
-
-Implementing them, however, is quite difficult. Moreso than I thought it would
-be. The big inhibitor is the method by which I actually pass input data into the
-function's body. From an implementation standpoint it's difficult because I
-*need* to know how many bytes on the stack the arguments take up. From a syntax
-standpoint this is difficult without a type annotation system. And from a
-usability standpoint this is difficult because it's a task the programmer has to
-do which doesn't really have to do with the actual purpose or content of the
-function, it's just a book-keeping exercise.
-
-So the stack is what's screwing us over here. It's a nice idea, but ultimately
-makes what we're trying to do difficult. I'm not sure if there's ever going to
-be a method of implementing pure functions that doesn't involve argument/return
-value copying though, and therefore which doesn't involve knowing the byte size
-of your arguments ahead of time.
-
-It's probably not worth backtracking this much either. For starters, cpus are
-heavily optimized for stack based operations, and much of the way we currently
-think about programming is also based on the stack. It would take a lot of
-backtracking if we ever moved to something else, if there even is anything else
-worth moving to.
-
-If that's the case, how is the stack actually used then?
-
-* There's a stack pointer which points at an address on the stack, the stack
-  being a contiguous range of memory addresses. The place the stack points to is
-  the "top" of the stack, all higher addresses are considered unused (no matter
-  what's in them). All the values in the stack are available to the currently
-  executing code, it simply needs to know either their absolute address or their
-  relative position to the stack pointer.
-
-* When a function is "called" the arguments to it are copied onto the top of the
-  stack, the stack pointer is increased to reflect the new stack height, and the
-  function's body is jumped to. Inside the body the function need only pop
-  values off the stack as it expects them, as long as it was called properly it
-  doesn't matter how or when the function was called. Once it's done operating
-  the function ensures all the input values have been popped off the stack, and
-  subsequently pushes the return values onto the stack, and jumps back to the
-  caller (the return address was also stored on the stack).
-
-That's not quite right, but it's close enough for most cases. The more I'm
-reading about this the more I think it's not going to be worth it to backtrack
-passed the stack. There's a lot of compiler and machine specific crap that gets
-involved at that low of a level, and I don't think it's worth getting into it.
-LLVM did all of that for me, I should learn how to make use of that to make what
-I want happen.
-
-But what do I actually want? That's the hard part. I guess I've come full
-circle. I pretty much *need* to use llvm functions. But I can't do it without
-declaring the types ahead of time. Ugghh.
-
-################################
-
-So here's the current problem:
-
-I have the concept of a list of statements representing a code block. It's
-possible/probable that more than this will be needed to represent a code block,
-but we'll see.
-
-There's two different ways I think it's logical to use a block:
-
-* As a way of running statements within a new context which inherits all of its
-  bindings from the parent. This would be used for things like if statements and
-  loops, and behaves the way a code block behaves in most other languages.
-
-* To define a operator body. An operator's body is effectively the same as the
-  first use-case, except that it has input/output as well. An operator can be
-  bound to an identifier and used in any statement.
-
-So the hard part, really, is that second point. I have the first done already.
-The second one isn't too hard to "fake" using our current context system, but it
-can't be made to be used as an operator in a statement. Here's how to fake it
-though:
-
-* Define the list of statements
-* Make a new context
-* Bind the "input" bindings into the new context
-* Run %do with that new context and list of statements
-* Pull the "output" bindings out of that new context
-
-And that's it. It's a bit complicated but it ultimately works and effectively
-inlines a function call.
-
-It's important that this looks like a normal operator call though, because I
-believe in guy steele. Here's the current problems I'm having:
-
-* Defining the input/output values is the big one. In the inline method those
-  were defined implicitly based on what the statements actually use, and the
-  compiler would fail if any were missing or the wrong type. But here we ideally
-  want to define an actual llvm function and not inline everytime. So we need to
-  somehow "know" what the input/output is, and their types.
-
-    * The output value isn't actually *that* difficult. We just look at the
-      output type of the last statement in the list and use that.
-
-    * The input is where it gets tricky. One idea would be to use a statement
-      with no input as the first statement in the list, and that would define
-      the input type. The way macros work this could potentially "just work",
-      but it's tricky.
-
-    * It would also be kind of difficult to make work with operators that take
-      in multiple parameters too. For example, `bind A, 1` would be the normal
-      syntax for binding, but if we want to bind an input value it gets weirder.
-
-        * We could use a "future" kind of syntax, like `bind A, _` or something
-          like that, but that would requre a new expression type and also just
-          be kind of weird.
-
-        * We could have a single macro which always returns the input, like
-          `%in` or something. So the bind would become `bind A, %in` or
-          `bind (A, B), %in` if we ever get destructuring. This isn't a terrible
-          solution, though a bit unfortunate in that it could get confusing with
-          different operators all using the same input variable effectively. It
-          also might be a bit difficult to implement, since it kind of forces us
-          to only have a single argument to the LLVM function? Hard to say how
-          that would work. Possibly all llvm functions could be made to take in
-          a struct, but that would be ghetto af. Not doing a struct would take a
-          special interaction though.... It might not be possible to do this
-          without a struct =/
-
-* Somehow allowing to define the context which gets used on each call to the
-  operator, instead of always using a blank one, would be nice.
-
-    * The big part of this problem is actually the syntax for calling the
-      operator. It's pretty easy to have this handled within the operator by the
-      %thisctx macro. But we want the operator to be callable by the same syntax
-      as all other operator calls, and currently that doesn't have any way of
-      passing in a new context.
-
-    * Additionally, if we're implementing the operator as an LLVM function then
-      there's not really any way to pass in that context to it without making
-      those variables global or something, which is shitty.
-
-* So writing all this out it really feels like I'm dealing with two separate
-  types that just happen to look similar:
-
-    * Block: a list of statements which run with a variable context.
-
-    * Operator: a list of statements which run with a fixed (empty?) context,
-      and have input/output.
-
-* There's so very nearly a symmetry there. Things that are inconsistent:
-
-    * A block doesn't have input/output
-
-        * It sort of does, in the form of the context it's being run with and
-          %ctxget, but not an explicit input/output like the operator has.
-
-        * If this could be reconciled I think this whole shitshow could be made
-          to have some consistency.
-
-        * Using %in this pretty much "just works". But it's still weird. Really
-          we'd want to turn the block into a one-off operator everytime we use
-          it. This is possible.
-
-    * An operator's context must be empty
-
-        * It doesn't *have* to be, defining the ctx which goes with the operator
-          could be part of however an operator is created.
-
-* So after all of that, I think operators and blocks are kind of the same.
-
-    * They both use %in to take in input, and both output using the last statement
-      in their list of statements.
-
-    * They both have a context bound to them, operators are fixed but a block
-      changes.
-
-    * An operator is a block with a bound context.
-
-##############@@@@@@@@@#$%^&^%$#@#$%^&*
-
-* New problem: type inference. LLVM requires that a function's definition have
-  the type specified up-front. This kind of blows. Well actually, it blows a lot
-  more than kind of. There's two things that need to be infered from a List of
-  Statements then: the input type and the output type. There's two approaches
-  I've thought of in the current setup.
-
-    * There's two approaches to determining the type of an operator: analyze the
-      code as ginger expressions, or build the actual llvm structures and
-      analyze those.
-
-        * Looking at the ginger expressions is definitely somewhat fuzzy. We can
-          look at all the statements and sub-statements until we find an
-          instance of %in, then look at what that's in input into. But if it's
-          simply binding into an Identifier then we have to find the identifier.
-          If it's destructuring then that gets even *more* complicated.
-
-            * Destructuring is what really makes this approach difficult.
-              Presumably there's going to be a function that takes in an
-              Identifier (or %in I guess?) and a set of Statements and returns
-              the type for that Identifier. If we find that %in is destructured
-              into a tuple then we would run that function for each constituent
-              Identifier and put it all together. But then this inference
-              function is really coupled to %bind, which kind of blows. Also we
-              may one day want to support destructuring into non-tuples as well,
-              which would make this even harder.
-
-            * We could make it the job of the macro definition to know its input
-              and output types, as well as the types of any bindings it makes.
-              That places some burden on user macros in the future, but then
-              maybe it can be inferred for user macros? That's a lot of hope. It
-              would also mean the macro would need the full set of statements
-              that will ever run in the same Context as it, so it can determine
-              the types of any bindings it makes.
-
-       * The second method is to build the statements into LLVM structures and
-         then look at those structures. This has the benefit of being
-         non-ambiguous once we actually find the answer. LLVM is super strongly
-         typed, and re-iterates the types involved for every operation. So if
-         the llvm builder builds it then we need only look for the first usage
-         of every argument/return and we'll know the types involved.
-
-            * This requires us to use structs for tuples, and not actually use
-              multiple arguments. Otherwise it won't be possible to know the
-              difference between a 3 argument function and a 4 argument one
-              which doesn't use its 4th argument (which shouldn't really happen,
-              but could).
-
-            * The main hinderence is that the llvm builder is really not
-              designed for this sort of thing. We could conceivably create a
-              "dummy" function with bogus types and write the body, analyze the
-              body, erase the function, and start over with a non-dummy
-              function. But it's the "analyze the body" step that's difficult.
-              It's difficult to find the types of things without the llvm.Value
-              objects in hand, but since building is set up as a recursive
-              process that becomes non-trivial. This really feels like the way
-              to go though, I think it's actually doable.
-
-                * This could be something we tack onto llvmVal, and then make
-                  Build return extra data about what types the Statements it
-                  handled input and output.
-
-* For other setups that would enable this a bit better, the one that keeps
-  coming to mind is a more pipeline style system. Things like %bind would need
-  to be refactored from something that takes a Tuple to something that only
-  takes an Identifier and returns a macro which will bind to that Identifier.
-  This doesn't *really* solve the type problem I guess, since whatever is input
-  into the Identifier's bind doesn't necessarily have a type attached to it.
-  Sooo yeah nvm.

README.md

@@ -1,118 +1,29 @@
-# Ginger - holy fuck again?
+# Ginger
 
-## The final result. A language which can do X
+A programming language utilizing a graph datastructure for syntax. Currently in
+super-early-alpha-don't-actually-use-this-for-anything development.
 
-- Support my OS
-    - Compile on many architectures
-    - Be low level and fast (effectively c-level)
-    - Be well defined, using a simple syntax
-    - Extensible based on which section of the OS I'm working on
-    - Good error messages
+## Development
 
-- Support other programmers and other programming areas
-    - Effectively means able to be used in most purposes
-    - Able to be quickly learned
-    - Able to be shared
-        - Free
-        - New or improved components shared between computers/platforms/people
+Current efforts on ginger are focused on a golang-based virtual machine, which
+will then be used to bootstrap the language.
 
-- Support itself
-    - Garner a team to work on the compiler
-        - Team must not require my help for day-to-day
-        - Team must stick to the manifesto, either through the design or through
-          trust
+If you are on a machine with nix installed, you can run:
 
-## The language: A manifesto, defines the concept of the language
+```
+nix develop
+```
 
-- Quips
-    - Easier is not better
+from the repo root and you will be dropped into a shell with all dependencies
+(including the correct go version) in your PATH, ready to use.
 
-- Data as the language
-    - Differentiation between "syntax" and "language", parser vs compiler
-        - Syntax defines the form which is parsed
-            - The parser reads the syntax forms into data structures
-        - Language defines how the syntax is read into data structures and
-          "understood" (i.e. and what is done with those structures).
-            - A language maybe have multiple syntaxes, if they all parse into
-              the same underlying data structures they can be understood in the
-              same way.
-            - A compiler turns the parsed language into machine code. An
-              interpreter performs actions directly based off of the parsed
-              language.
+## Demo
 
-- Types, instances, and operations
-    - A language has a set of elemental types, and composite types
-        - "The type defines the [fundamental] operations that can be done on the
-          data, the meaning of the data, and the way values of that type can be
-          stored"
-        - Elemental types are all forms of numbers, since numbers are all a
-          computer really knows
-        - Composite types take two forms:
-            - Homogeneous: all composed values are the same type (arrays)
-            - Heterogeneous: all composed values are different
-                - If known size and known types per-index, tuples
-                - A 0-tuple is kind of special, and simply indicates absence of
-                  any value.
-        - A third type, Any, indicates that the type is unknown at compile-time.
-          Type information must be passed around with it at runtime.
-        - An operation has an input and output. It does some action on the input
-          to produce the output (presumably). An operation may be performed as
-          many times as needed, given any value of the input type. The types of
-          both the input and output are constant, and together they form the
-          operation's type.
-    - A value is an instance of a type, where the type is known at compile-time
-      (though the type may be Any). Multiple values may be instances of the same
-      type. E.g.: 1 and 2 are both instances of int
-        - A value is immutable
-        - TODO value is a weird word, since an instance of a type has both a
-          type and value. I need to think about this more. Instance might be a
-          better name
+An example program which computes the Nth fibonacci number can be found at
+`examples/fib.gg`. You can try it out by doing:
 
-- Stack and scope
-    - A function call operates within a scope. The scope had arguments passed
-      into it.
-    - When a function calls another, that other's scope is said to be "inside"
-      the caller's scope.
-    - A pure function only operates on the arguments passed into it.
-    - A pointer allows for modification outside of the current scope, but only a
-      pointer into an outer scope. A function which does this is "impure"
+```
+go run ./cmd/eval/main.go "$(cat examples/fib.gg)" 5
+```
 
-- Built-in
-    - Elementals
-        - ints (n-bit)
-        - tuples
-        - stack arrays
-            - indexable
-            - head/tail
-            - reversible (?)
-            - appendable
-        - functions (?)
-        - pointers (?)
-        - Any (?)
-    - Elementals must be enough to define the type of a variable
-    - Ability to create and modify elmental types
-        - immutable, pure functions
-    - Other builtin functionality:
-        - Load/call linked libraries
-    - Comiletime macros
-        - Red/Blue
-
-- Questions
-    - Strings need to be defined in terms of the built-in types, which would be
-      an array of lists. But this means I'm married to that definition of a
-      string, it'd be difficult for anyone to define their own and have it
-      interop. Unless "int" was some kind of macro type that did some fancy
-      shit, but that's kind of gross.
-    - An idea of the "equality" of two variables being tied not just to their
-      value but to the context in which they were created. Would aid in things
-      like compiler tagging.
-    - There's a "requirement loop" of things which need figuring out:
-        - function structure
-        - types
-        - seq type
-        - stack/scope
-    - Most likely I'm going to need some kind of elemental type to indicate
-      something should happen at compile-time and not runtime, or the other way
-      around.
-
-## The roadmap: A plan of action for tackling the language
+Where you can replace `5` with any number.

cmd/eval/main.go

@@ -0,0 +1,37 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+
+	"code.betamike.com/mediocregopher/ginger/gg"
+	"code.betamike.com/mediocregopher/ginger/vm"
+)
+
+func main() {
+
+	if len(os.Args) < 3 {
+		fmt.Printf(`Usage: %s <operation source> "in = <value>"\n`, os.Args[0])
+		return
+	}
+
+	opSrc := os.Args[1]
+	inSrc := os.Args[2]
+
+	inVal, err := gg.NewDecoder(bytes.NewBufferString(inSrc)).Next()
+	if err != nil {
+		panic(fmt.Sprintf("decoding input: %v", err))
+	}
+
+	res, err := vm.EvaluateSource(
+		bytes.NewBufferString(opSrc),
+		vm.Value{Value: inVal.Value},
+		vm.GlobalScope,
+	)
+	if err != nil {
+		panic(fmt.Sprintf("evaluating: %v", err))
+	}
+
+	fmt.Println(res)
+}

examples/examples_test.go

@@ -0,0 +1,53 @@
+package examples_test
+
+import (
+	"embed"
+	"fmt"
+	"testing"
+
+	"code.betamike.com/mediocregopher/ginger/gg"
+	"code.betamike.com/mediocregopher/ginger/vm"
+	"github.com/stretchr/testify/assert"
+)
+
+//go:embed *.gg
+var examplesFS embed.FS
+
+func TestAllExamples(t *testing.T) {
+
+	tests := []struct {
+		path string
+		in   vm.Value
+		exp  vm.Value
+	}{
+		{
+			path: "fib.gg",
+			in:   vm.Value{Value: gg.Number(5)},
+			exp:  vm.Value{Value: gg.Number(5)},
+		},
+		{
+			path: "fib.gg",
+			in:   vm.Value{Value: gg.Number(10)},
+			exp:  vm.Value{Value: gg.Number(55)},
+		},
+		{
+			path: "fib.gg",
+			in:   vm.Value{Value: gg.Number(69)},
+			exp:  vm.Value{Value: gg.Number(117669030460994)},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(fmt.Sprintf("%s_%v", test.path, test.in), func(t *testing.T) {
+			f, err := examplesFS.Open(test.path)
+			if err != nil {
+				t.Fatal(err)
+			}
+			defer f.Close()
+
+			got, err := vm.EvaluateSource(f, test.in, vm.GlobalScope)
+			assert.NoError(t, err)
+			assert.True(t, test.exp.Equal(got), "%v != %v", test.exp, got)
+		})
+	}
+}

examples/fib.gg

@@ -0,0 +1,24 @@
+* A function which accepts a number N and returns the Nth fibonacci number
+{
+    * We are passing a tuple of inputs into a graph here, such that the graph is
+    * evaluated as an anonymous function. That anonymous function uses !recur
+    * internally to compute the result.
+    !out = {
+
+        * A little helper function.
+        decr = { !out = !add < (!in, -1) };
+
+        * Deconstruct the input tuple into its individual elements, for clarity.
+        * There will be a more ergonomic way of doing this one day.
+        n = !tupEl < (!in, 0);
+        a = !tupEl < (!in, 1);
+        b = !tupEl < (!in, 2);
+
+        !out = !if < (
+            !isZero < n,
+            a,
+            !recur < ( decr<n, b, !add<(a,b) ),
+        );
+
+    } < (!in, 0, 1);
+}

expr/build.go

@@ -1,219 +0,0 @@
-package expr
-
-import (
-	"fmt"
-	"log"
-
-	"llvm.org/llvm/bindings/go/llvm"
-)
-
-func init() {
-	log.Printf("initializing llvm")
-	llvm.LinkInMCJIT()
-	llvm.InitializeNativeTarget()
-	llvm.InitializeNativeAsmPrinter()
-}
-
-type BuildCtx struct {
-	B llvm.Builder
-	M llvm.Module
-}
-
-func NewBuildCtx(moduleName string) BuildCtx {
-	return BuildCtx{
-		B: llvm.NewBuilder(),
-		M: llvm.NewModule(moduleName),
-	}
-}
-
-func (bctx BuildCtx) Build(ctx Ctx, stmts ...Statement) llvm.Value {
-	var lastVal llvm.Value
-	for _, stmt := range stmts {
-		if e := bctx.BuildStmt(ctx, stmt); e != nil {
-			if lv, ok := e.(llvmVal); ok {
-				lastVal = llvm.Value(lv)
-			} else {
-				log.Printf("BuildStmt returned non llvmVal from %v: %v (%T)", stmt, e, e)
-			}
-		}
-	}
-	if (lastVal == llvm.Value{}) {
-		lastVal = bctx.B.CreateRetVoid()
-	}
-	return lastVal
-}
-
-func (bctx BuildCtx) BuildStmt(ctx Ctx, s Statement) Expr {
-	log.Printf("building: %v", s)
-	switch o := s.Op.(type) {
-	case Macro:
-		return ctx.Macro(o)(bctx, ctx, s.Arg)
-	case Identifier:
-		s2 := s
-		s2.Op = ctx.Identifier(o).(llvmVal)
-		return bctx.BuildStmt(ctx, s2)
-	case Statement:
-		s2 := s
-		s2.Op = bctx.BuildStmt(ctx, o)
-		return bctx.BuildStmt(ctx, s2)
-	case llvmVal:
-		arg := bctx.buildExpr(ctx, s.Arg).(llvmVal)
-		out := bctx.B.CreateCall(llvm.Value(o), []llvm.Value{llvm.Value(arg)}, "")
-		return llvmVal(out)
-	default:
-		panic(fmt.Sprintf("non op type %v (%T)", s.Op, s.Op))
-	}
-}
-
-// may return nil if e is a Statement which has no return
-func (bctx BuildCtx) buildExpr(ctx Ctx, e Expr) Expr {
-	return bctx.buildExprTill(ctx, e, func(Expr) bool { return false })
-}
-
-// like buildExpr, but will stop short and stop recursing when the function
-// returns true
-func (bctx BuildCtx) buildExprTill(ctx Ctx, e Expr, fn func(e Expr) bool) Expr {
-	if fn(e) {
-		return e
-	}
-
-	switch ea := e.(type) {
-	case llvmVal:
-		return e
-	case Int:
-		return llvmVal(llvm.ConstInt(llvm.Int64Type(), uint64(ea), false))
-	case Identifier:
-		return ctx.Identifier(ea)
-	case Statement:
-		return bctx.BuildStmt(ctx, ea)
-	case Tuple:
-		// if the tuple is empty then it is a void
-		if len(ea) == 0 {
-			return llvmVal(llvm.Undef(llvm.VoidType()))
-		}
-
-		ea2 := make(Tuple, len(ea))
-		for i := range ea {
-			ea2[i] = bctx.buildExprTill(ctx, ea[i], fn)
-		}
-
-		// if the fields of the tuple are all llvmVal then we can make a proper
-		// struct
-		vals := make([]llvm.Value, len(ea2))
-		typs := make([]llvm.Type, len(ea2))
-		for i := range ea2 {
-			if v, ok := ea2[i].(llvmVal); ok {
-				val := llvm.Value(v)
-				vals[i] = val
-				typs[i] = val.Type()
-			} else {
-				return ea2
-			}
-		}
-
-		str := llvm.Undef(llvm.StructType(typs, false))
-		for i := range vals {
-			str = bctx.B.CreateInsertValue(str, vals[i], i, "")
-		}
-		return llvmVal(str)
-	case List:
-		ea2 := make(Tuple, len(ea))
-		for i := range ea {
-			ea2[i] = bctx.buildExprTill(ctx, ea[i], fn)
-		}
-		return ea2
-	case Ctx:
-		return ea
-	default:
-		panicf("%v (type %T) can't express a value", ea, ea)
-	}
-	panic("go is dumb")
-}
-
-func (bctx BuildCtx) buildVal(ctx Ctx, e Expr) llvm.Value {
-	return llvm.Value(bctx.buildExpr(ctx, e).(llvmVal))
-}
-
-// globalCtx describes what's available to *all* contexts, and is what all
-// contexts should have as the root parent in the tree.
-//
-// We define in this weird way cause NewCtx actually references globalCtx
-var globalCtx *Ctx
-var _ = func() bool {
-	globalCtx = &Ctx{
-		macros: map[Macro]MacroFn{
-			"add": func(bctx BuildCtx, ctx Ctx, e Expr) Expr {
-				tup := bctx.buildExpr(ctx, e).(llvmVal)
-				a := bctx.B.CreateExtractValue(llvm.Value(tup), 0, "")
-				b := bctx.B.CreateExtractValue(llvm.Value(tup), 1, "")
-				return llvmVal(bctx.B.CreateAdd(a, b, ""))
-			},
-
-			// TODO this chould be a user macro!!!! WUT this language is baller
-			"bind": func(bctx BuildCtx, ctx Ctx, e Expr) Expr {
-				tup := bctx.buildExprTill(ctx, e, isIdentifier).(Tuple)
-				id := bctx.buildExprTill(ctx, tup[0], isIdentifier).(Identifier)
-				val := bctx.buildExpr(ctx, tup[1])
-				ctx.Bind(id, val)
-				return NewTuple()
-			},
-
-			"ctxnew": func(bctx BuildCtx, ctx Ctx, e Expr) Expr {
-				return NewCtx()
-			},
-
-			"ctxthis": func(bctx BuildCtx, ctx Ctx, e Expr) Expr {
-				return ctx
-			},
-
-			"ctxbind": func(bctx BuildCtx, ctx Ctx, e Expr) Expr {
-				tup := bctx.buildExprTill(ctx, e, isIdentifier).(Tuple)
-				thisCtx := bctx.buildExpr(ctx, tup[0]).(Ctx)
-				id := bctx.buildExprTill(ctx, tup[1], isIdentifier).(Identifier)
-				thisCtx.Bind(id, bctx.buildExpr(ctx, tup[2]))
-				return NewTuple()
-			},
-
-			"ctxget": func(bctx BuildCtx, ctx Ctx, e Expr) Expr {
-				tup := bctx.buildExprTill(ctx, e, isIdentifier).(Tuple)
-				thisCtx := bctx.buildExpr(ctx, tup[0]).(Ctx)
-				id := bctx.buildExprTill(ctx, tup[1], isIdentifier).(Identifier)
-				return thisCtx.Identifier(id)
-			},
-
-			"do": func(bctx BuildCtx, ctx Ctx, e Expr) Expr {
-				tup := bctx.buildExprTill(ctx, e, isStmt).(Tuple)
-				thisCtx := tup[0].(Ctx)
-				for _, stmtE := range tup[1].(List) {
-					bctx.BuildStmt(thisCtx, stmtE.(Statement))
-				}
-				return NewTuple()
-			},
-
-			"op": func(bctx BuildCtx, ctx Ctx, e Expr) Expr {
-				l := bctx.buildExprTill(ctx, e, isList).(List)
-				stmts := make([]Statement, len(l))
-				for i := range l {
-					stmts[i] = l[i].(Statement)
-				}
-
-				// TODO obviously this needs to be fixed
-				fn := llvm.AddFunction(bctx.M, "", llvm.FunctionType(llvm.Int64Type(), []llvm.Type{llvm.Int64Type()}, false))
-				fnbl := llvm.AddBasicBlock(fn, "")
-
-				prevbl := bctx.B.GetInsertBlock()
-				bctx.B.SetInsertPoint(fnbl, fnbl.FirstInstruction())
-				out := bctx.Build(NewCtx(), stmts...)
-				bctx.B.CreateRet(out)
-				bctx.B.SetInsertPointAtEnd(prevbl)
-				return llvmVal(fn)
-			},
-
-			"in": func(bctx BuildCtx, ctx Ctx, e Expr) Expr {
-				fn := bctx.B.GetInsertBlock().Parent()
-				return llvmVal(fn.Param(0))
-			},
-		},
-	}
-	return false
-}()

expr/build_test.go

@@ -1,99 +0,0 @@
-package expr
-
-import (
-	"fmt"
-	. "testing"
-
-	"llvm.org/llvm/bindings/go/llvm"
-)
-
-func buildTest(t *T, expected int64, stmts ...Statement) {
-	fmt.Println("-----------------------------------------")
-	ctx := NewCtx()
-	bctx := NewBuildCtx("")
-
-	fn := llvm.AddFunction(bctx.M, "", llvm.FunctionType(llvm.Int64Type(), []llvm.Type{}, false))
-	fnbl := llvm.AddBasicBlock(fn, "")
-	bctx.B.SetInsertPoint(fnbl, fnbl.FirstInstruction())
-	out := bctx.Build(ctx, stmts...)
-	bctx.B.CreateRet(out)
-
-	fmt.Println("######## dumping IR")
-	bctx.M.Dump()
-	fmt.Println("######## done dumping IR")
-
-	if err := llvm.VerifyModule(bctx.M, llvm.ReturnStatusAction); err != nil {
-		t.Fatal(err)
-	}
-
-	eng, err := llvm.NewExecutionEngine(bctx.M)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	res := eng.RunFunction(fn, []llvm.GenericValue{}).Int(false)
-	if int64(res) != expected {
-		t.Errorf("expected:[%T]%v actual:[%T]%v", expected, expected, res, res)
-	}
-}
-
-func TestAdd(t *T) {
-	buildTest(t, 2,
-		NewStatement(Macro("add"), Int(1), Int(1)))
-	buildTest(t, 4,
-		NewStatement(Macro("add"), Int(1),
-			NewStatement(Macro("add"), Int(1), Int(2))))
-	buildTest(t, 6,
-		NewStatement(Macro("add"),
-			NewStatement(Macro("add"), Int(1), Int(2)),
-			NewStatement(Macro("add"), Int(1), Int(2))))
-}
-
-func TestBind(t *T) {
-	buildTest(t, 2,
-		NewStatement(Macro("bind"), Identifier("A"), Int(1)),
-		NewStatement(Macro("add"), Identifier("A"), Int(1)))
-	buildTest(t, 2,
-		NewStatement(Macro("bind"), Identifier("A"), Int(1)),
-		NewStatement(Macro("add"), Identifier("A"), Identifier("A")))
-	buildTest(t, 2,
-		NewStatement(Macro("bind"), Identifier("A"), NewTuple(Int(1), Int(1))),
-		NewStatement(Macro("add"), Identifier("A")))
-	buildTest(t, 3,
-		NewStatement(Macro("bind"), Identifier("A"), NewTuple(Int(1), Int(1))),
-		NewStatement(Macro("add"), Int(1),
-			NewStatement(Macro("add"), Identifier("A"))))
-	buildTest(t, 4,
-		NewStatement(Macro("bind"), Identifier("A"), NewTuple(Int(1), Int(1))),
-		NewStatement(Macro("add"),
-			NewStatement(Macro("add"), Identifier("A")),
-			NewStatement(Macro("add"), Identifier("A"))))
-}
-
-func TestOp(t *T) {
-	incr := NewStatement(Macro("op"),
-		NewList(
-			NewStatement(Macro("add"), Int(1), NewStatement(Macro("in"))),
-		),
-	)
-
-	// bound op
-	buildTest(t, 2,
-		NewStatement(Macro("bind"), Identifier("incr"), incr),
-		NewStatement(Identifier("incr"), Int(1)))
-
-	// double bound op
-	buildTest(t, 3,
-		NewStatement(Macro("bind"), Identifier("incr"), incr),
-		NewStatement(Identifier("incr"),
-			NewStatement(Identifier("incr"), Int(1))))
-
-	// anon op
-	buildTest(t, 2,
-		NewStatement(incr, Int(1)))
-
-	// double anon op
-	buildTest(t, 3,
-		NewStatement(incr,
-			NewStatement(incr, Int(1))))
-}

expr/ctx.go

@@ -1,72 +0,0 @@
-package expr
-
-// MacroFn is a compiler function which takes in an existing Expr and returns
-// the llvm Value for it
-type MacroFn func(BuildCtx, Ctx, Expr) Expr
-
-// Ctx contains all the Macros and Identifiers available. A Ctx also keeps a
-// reference to the global context, which has a number of macros available for
-// all contexts to use.
-type Ctx struct {
-	global *Ctx
-	macros map[Macro]MacroFn
-	idents map[Identifier]Expr
-}
-
-// NewCtx returns a blank context instance
-func NewCtx() Ctx {
-	return Ctx{
-		global: globalCtx,
-		macros: map[Macro]MacroFn{},
-		idents: map[Identifier]Expr{},
-	}
-}
-
-// Macro returns the MacroFn associated with the given identifier, or panics
-// if the macro isn't found
-func (c Ctx) Macro(m Macro) MacroFn {
-	if fn := c.macros[m]; fn != nil {
-		return fn
-	}
-	if fn := c.global.macros[m]; fn != nil {
-		return fn
-	}
-	panicf("macro %q not found in context", m)
-	return nil
-}
-
-// Identifier returns the llvm.Value for the Identifier, or panics
-func (c Ctx) Identifier(i Identifier) Expr {
-	if e := c.idents[i]; e != nil {
-		return e
-	}
-	// The global context doesn't have any identifiers, so don't bother checking
-	panicf("identifier %q not found", i)
-	panic("go is dumb")
-}
-
-// Copy returns a deep copy of the Ctx
-func (c Ctx) Copy() Ctx {
-	cc := Ctx{
-		global: c.global,
-		macros: make(map[Macro]MacroFn, len(c.macros)),
-		idents: make(map[Identifier]Expr, len(c.idents)),
-	}
-	for m, mfn := range c.macros {
-		cc.macros[m] = mfn
-	}
-	for i, e := range c.idents {
-		cc.idents[i] = e
-	}
-	return cc
-}
-
-// Bind returns a new Ctx which is a copy of this one, but with the given
-// Identifier bound to the given Expr. Will panic if the Identifier is already
-// bound
-func (c Ctx) Bind(i Identifier, e Expr) {
-	if _, ok := c.idents[i]; ok {
-		panicf("identifier %q is already bound", i)
-	}
-	c.idents[i] = e
-}

expr/expr.go

@@ -1,210 +0,0 @@
-package expr
-
-import (
-	"fmt"
-
-	"llvm.org/llvm/bindings/go/llvm"
-)
-
-// Expr represents the actual expression in question.
-type Expr interface{}
-
-// equaler is used to compare two expressions. The comparison should not take
-// into account Token values, only the actual value being represented
-type equaler interface {
-	equal(equaler) bool
-}
-
-// will panic if either Expr doesn't implement equaler
-func exprEqual(e1, e2 Expr) bool {
-	eq1, ok1 := e1.(equaler)
-	eq2, ok2 := e2.(equaler)
-	if !ok1 || !ok2 {
-		panic(fmt.Sprintf("can't compare %T and %T", e1, e2))
-	}
-	return eq1.equal(eq2)
-}
-
-////////////////////////////////////////////////////////////////////////////////
-
-// an Expr which simply wraps an existing llvm.Value
-type llvmVal llvm.Value
-
-/*
-func voidVal(lctx LLVMCtx) llvmVal {
-	return llvmVal{lctx.B.CreateRetVoid()}
-}
-*/
-
-////////////////////////////////////////////////////////////////////////////////
-
-/*
-// Void represents no data (size = 0)
-type Void struct{}
-
-func (v Void) equal(e equaler) bool {
-	_, ok := e.(Void)
-	return ok
-}
-*/
-
-////////////////////////////////////////////////////////////////////////////////
-/*
-// Bool represents a true or false value
-type Bool bool
-
-func (b Bool) equal(e equaler) bool {
-	bb, ok := e.(Bool)
-	if !ok {
-		return false
-	}
-	return bb == b
-}
-*/
-////////////////////////////////////////////////////////////////////////////////
-
-// Int represents an integer value
-type Int int64
-
-func (i Int) equal(e equaler) bool {
-	ii, ok := e.(Int)
-	return ok && ii == i
-}
-
-func (i Int) String() string {
-	return fmt.Sprintf("%d", i)
-}
-
-////////////////////////////////////////////////////////////////////////////////
-/*
-// String represents a string value
-type String string
-
-func (s String) equal(e equaler) bool {
-	ss, ok := e.(String)
-	if !ok {
-		return false
-	}
-	return ss == s
-}
-*/
-////////////////////////////////////////////////////////////////////////////////
-
-// Identifier represents a binding to some other value which has been given a
-// name
-type Identifier string
-
-func (id Identifier) equal(e equaler) bool {
-	idid, ok := e.(Identifier)
-	return ok && idid == id
-}
-
-func isIdentifier(e Expr) bool {
-	_, ok := e.(Identifier)
-	return ok
-}
-
-////////////////////////////////////////////////////////////////////////////////
-
-// Macro is an identifier for a macro which can be used to transform
-// expressions. The tokens for macros start with a '%', but the Macro identifier
-// itself has that stripped off
-type Macro string
-
-// String returns the Macro with a '%' prepended to it
-func (m Macro) String() string {
-	return "%" + string(m)
-}
-
-func (m Macro) equal(e equaler) bool {
-	mm, ok := e.(Macro)
-	return ok && m == mm
-}
-
-////////////////////////////////////////////////////////////////////////////////
-
-// Tuple represents a fixed set of expressions which are interacted with as if
-// they were a single value
-type Tuple []Expr
-
-// NewTuple returns a Tuple around the given list of Exprs
-func NewTuple(ee ...Expr) Tuple {
-	return Tuple(ee)
-}
-
-func (tup Tuple) String() string {
-	return "(" + exprsJoin(tup) + ")"
-}
-
-func (tup Tuple) equal(e equaler) bool {
-	tuptup, ok := e.(Tuple)
-	return ok && exprsEqual(tup, tuptup)
-}
-
-func isTuple(e Expr) bool {
-	_, ok := e.(Tuple)
-	return ok
-}
-
-////////////////////////////////////////////////////////////////////////////////
-
-// List represents an ordered set of Exprs, all of the same type. A List's size
-// does not affect its type signature, unlike a Tuple
-type List []Expr
-
-// NewList returns a List around the given list of Exprs
-func NewList(ee ...Expr) List {
-	return List(ee)
-}
-
-func (l List) String() string {
-	return "[" + exprsJoin(l) + "]"
-}
-
-func (l List) equal(e equaler) bool {
-	ll, ok := e.(List)
-	return ok && exprsEqual(l, ll)
-}
-
-func isList(e Expr) bool {
-	_, ok := e.(List)
-	return ok
-}
-
-////////////////////////////////////////////////////////////////////////////////
-
-// Statement represents an actual action which will be taken. The input value is
-// used as the input to the pipe, and the output of the pipe is the output of
-// the statement
-type Statement struct {
-	Op, Arg Expr
-}
-
-// NewStatement returns a Statement whose Op is the first Expr. If the given
-// list is empty Arg will be 0-tuple, if its length is one Arg will be that
-// single Expr, otherwise Arg will be a Tuple of the list
-func NewStatement(e Expr, ee ...Expr) Statement {
-	s := Statement{Op: e}
-	if len(ee) > 1 {
-		s.Arg = NewTuple(ee...)
-	} else if len(ee) == 1 {
-		s.Arg = ee[0]
-	} else if len(ee) == 0 {
-		s.Arg = NewTuple()
-	}
-	return s
-}
-
-func (s Statement) String() string {
-	return fmt.Sprintf("(%v %s)", s.Op, s.Arg)
-}
-
-func (s Statement) equal(e equaler) bool {
-	ss, ok := e.(Statement)
-	return ok && exprEqual(s.Op, ss.Op) && exprEqual(s.Arg, ss.Arg)
-}
-
-func isStmt(e Expr) bool {
-	_, ok := e.(Statement)
-	return ok
-}

expr/parse.go

@@ -1,299 +0,0 @@
-package expr
-
-//type exprErr struct {
-//	reason string
-//	err    error
-//	tok    lexer.Token
-//	tokCtx string // e.g. "block starting at" or "open paren at"
-//}
-//
-//func (e exprErr) Error() string {
-//	var msg string
-//	if e.err != nil {
-//		msg = e.err.Error()
-//	} else {
-//		msg = e.reason
-//	}
-//	if err := e.tok.Err(); err != nil {
-//		msg += " - token error: " + err.Error()
-//	} else if (e.tok != lexer.Token{}) {
-//		msg += " - "
-//		if e.tokCtx != "" {
-//			msg += e.tokCtx + ": "
-//		}
-//		msg = fmt.Sprintf("%s [line:%d col:%d]", msg, e.tok.Row, e.tok.Col)
-//	}
-//	return msg
-//}
-//
-//////////////////////////////////////////////////////////////////////////////////
-//
-//// toks[0] must be start
-//func sliceEnclosedToks(toks []lexer.Token, start, end lexer.Token) ([]lexer.Token, []lexer.Token, error) {
-//	c := 1
-//	ret := []lexer.Token{}
-//	first := toks[0]
-//	for i, tok := range toks[1:] {
-//		if tok.Err() != nil {
-//			return nil, nil, exprErr{
-//				reason: fmt.Sprintf("missing closing %v", end),
-//				tok:    tok,
-//			}
-//		}
-//
-//		if tok.Equal(start) {
-//			c++
-//		} else if tok.Equal(end) {
-//			c--
-//		}
-//		if c == 0 {
-//			return ret, toks[2+i:], nil
-//		}
-//		ret = append(ret, tok)
-//	}
-//
-//	return nil, nil, exprErr{
-//		reason: fmt.Sprintf("missing closing %v", end),
-//		tok:    first,
-//		tokCtx: "starting at",
-//	}
-//}
-//
-//// Parse reads in all expressions it can from the given io.Reader and returns
-//// them
-//func Parse(r io.Reader) ([]Expr, error) {
-//	toks := readAllToks(r)
-//	var ret []Expr
-//	var expr Expr
-//	var err error
-//	for len(toks) > 0 {
-//		if toks[0].TokenType == lexer.EOF {
-//			return ret, nil
-//		}
-//		expr, toks, err = parse(toks)
-//		if err != nil {
-//			return nil, err
-//		}
-//		ret = append(ret, expr)
-//	}
-//	return ret, nil
-//}
-//
-//// ParseAsBlock reads the given io.Reader as if it was implicitly surrounded by
-//// curly braces, making it into a Block. This means all expressions from the
-//// io.Reader *must* be statements. The returned Expr's Actual will always be a
-//// Block.
-//func ParseAsBlock(r io.Reader) (Expr, error) {
-//	return parseBlock(readAllToks(r))
-//}
-//
-//func readAllToks(r io.Reader) []lexer.Token {
-//	l := lexer.New(r)
-//	var toks []lexer.Token
-//	for l.HasNext() {
-//		toks = append(toks, l.Next())
-//	}
-//	return toks
-//}
-//
-//// For all parse methods it is assumed that toks is not empty
-//
-//var (
-//	openParen  = lexer.Token{TokenType: lexer.Wrapper, Val: "("}
-//	closeParen = lexer.Token{TokenType: lexer.Wrapper, Val: ")"}
-//	openCurly  = lexer.Token{TokenType: lexer.Wrapper, Val: "{"}
-//	closeCurly = lexer.Token{TokenType: lexer.Wrapper, Val: "}"}
-//	comma      = lexer.Token{TokenType: lexer.Punctuation, Val: ","}
-//	arrow      = lexer.Token{TokenType: lexer.Punctuation, Val: ">"}
-//)
-//
-//func parse(toks []lexer.Token) (Expr, []lexer.Token, error) {
-//	expr, toks, err := parseSingle(toks)
-//	if err != nil {
-//		return Expr{}, nil, err
-//	}
-//
-//	if len(toks) > 0 && toks[0].TokenType == lexer.Punctuation {
-//		return parseConnectingPunct(toks, expr)
-//	}
-//
-//	return expr, toks, nil
-//}
-//
-//func parseSingle(toks []lexer.Token) (Expr, []lexer.Token, error) {
-//	var expr Expr
-//	var err error
-//
-//	if toks[0].Err() != nil {
-//		return Expr{}, nil, exprErr{
-//			reason: "could not parse token",
-//			tok:    toks[0],
-//		}
-//	}
-//
-//	if toks[0].Equal(openParen) {
-//		starter := toks[0]
-//		var ptoks []lexer.Token
-//		ptoks, toks, err = sliceEnclosedToks(toks, openParen, closeParen)
-//		if err != nil {
-//			return Expr{}, nil, err
-//		}
-//
-//		if expr, ptoks, err = parse(ptoks); err != nil {
-//			return Expr{}, nil, err
-//		} else if len(ptoks) > 0 {
-//			return Expr{}, nil, exprErr{
-//				reason: "multiple expressions inside parenthesis",
-//				tok:    starter,
-//				tokCtx: "starting at",
-//			}
-//		}
-//		return expr, toks, nil
-//
-//	} else if toks[0].Equal(openCurly) {
-//		var btoks []lexer.Token
-//		btoks, toks, err = sliceEnclosedToks(toks, openCurly, closeCurly)
-//		if err != nil {
-//			return Expr{}, nil, err
-//		}
-//
-//		if expr, err = parseBlock(btoks); err != nil {
-//			return Expr{}, nil, err
-//		}
-//		return expr, toks, nil
-//	}
-//
-//	if expr, err = parseNonPunct(toks[0]); err != nil {
-//		return Expr{}, nil, err
-//	}
-//	return expr, toks[1:], nil
-//}
-//
-//func parseNonPunct(tok lexer.Token) (Expr, error) {
-//	if tok.TokenType == lexer.Identifier {
-//		return parseIdentifier(tok)
-//	} else if tok.TokenType == lexer.String {
-//		//return parseString(tok)
-//	}
-//
-//	return Expr{}, exprErr{
-//		reason: "unexpected non-punctuation token",
-//		tok:    tok,
-//	}
-//}
-//
-//func parseIdentifier(t lexer.Token) (Expr, error) {
-//	e := Expr{Token: t}
-//	if t.Val[0] == '-' || (t.Val[0] >= '0' && t.Val[0] <= '9') {
-//		n, err := strconv.ParseInt(t.Val, 10, 64)
-//		if err != nil {
-//			return Expr{}, exprErr{
-//				err: err,
-//				tok: t,
-//			}
-//		}
-//		e.Actual = Int(n)
-//
-//		/*
-//			} else if t.Val == "%true" {
-//				e.Actual = Bool(true)
-//
-//			} else if t.Val == "%false" {
-//				e.Actual = Bool(false)
-//		*/
-//
-//	} else if t.Val[0] == '%' {
-//		e.Actual = Macro(t.Val[1:])
-//
-//	} else {
-//		e.Actual = Identifier(t.Val)
-//	}
-//
-//	return e, nil
-//}
-//
-///*
-//func parseString(t lexer.Token) (Expr, error) {
-//	str, err := strconv.Unquote(t.Val)
-//	if err != nil {
-//		return Expr{}, exprErr{
-//			err: err,
-//			tok: t,
-//		}
-//	}
-//	return Expr{Token: t, Actual: String(str)}, nil
-//}
-//*/
-//
-//func parseConnectingPunct(toks []lexer.Token, root Expr) (Expr, []lexer.Token, error) {
-//	if toks[0].Equal(comma) {
-//		return parseTuple(toks, root)
-//
-//	} else if toks[0].Equal(arrow) {
-//		expr, toks, err := parse(toks[1:])
-//		if err != nil {
-//			return Expr{}, nil, err
-//		}
-//		return Expr{Token: root.Token, Actual: Statement{In: root, To: expr}}, toks, nil
-//	}
-//
-//	return root, toks, nil
-//}
-//
-//func parseTuple(toks []lexer.Token, root Expr) (Expr, []lexer.Token, error) {
-//	rootTup, ok := root.Actual.(Tuple)
-//	if !ok {
-//		rootTup = Tuple{root}
-//	}
-//
-//	// rootTup is modified throughout, be we need to make it into an Expr for
-//	// every return, which is annoying. so make a function to do it on the fly
-//	mkRoot := func() Expr {
-//		return Expr{Token: rootTup[0].Token, Actual: rootTup}
-//	}
-//
-//	if len(toks) < 2 {
-//		return mkRoot(), toks, nil
-//	} else if !toks[0].Equal(comma) {
-//		if toks[0].TokenType == lexer.Punctuation {
-//			return parseConnectingPunct(toks, mkRoot())
-//		}
-//		return mkRoot(), toks, nil
-//	}
-//
-//	var expr Expr
-//	var err error
-//	if expr, toks, err = parseSingle(toks[1:]); err != nil {
-//		return Expr{}, nil, err
-//	}
-//
-//	rootTup = append(rootTup, expr)
-//	return parseTuple(toks, mkRoot())
-//}
-//
-//// parseBlock assumes that the given token list is the entire block, already
-//// pulled from outer curly braces by sliceEnclosedToks, or determined to be the
-//// entire block in some other way.
-//func parseBlock(toks []lexer.Token) (Expr, error) {
-//	b := Block{}
-//	first := toks[0]
-//	var expr Expr
-//	var err error
-//	for {
-//		if len(toks) == 0 {
-//			return Expr{Token: first, Actual: b}, nil
-//		}
-//
-//		if expr, toks, err = parse(toks); err != nil {
-//			return Expr{}, err
-//		}
-//		if _, ok := expr.Actual.(Statement); !ok {
-//			return Expr{}, exprErr{
-//				reason: "blocks may only contain full statements",
-//				tok:    expr.Token,
-//				tokCtx: "non-statement here",
-//			}
-//		}
-//		b = append(b, expr)
-//	}
-//}

expr/parse_test.go

@@ -1,149 +0,0 @@
-package expr
-
-//import . "testing"
-
-//func TestSliceEnclosedToks(t *T) {
-//	doAssert := func(in, expOut, expRem []lexer.Token) {
-//		out, rem, err := sliceEnclosedToks(in, openParen, closeParen)
-//		require.Nil(t, err)
-//		assert.Equal(t, expOut, out)
-//		assert.Equal(t, expRem, rem)
-//	}
-//	foo := lexer.Token{TokenType: lexer.Identifier, Val: "foo"}
-//	bar := lexer.Token{TokenType: lexer.Identifier, Val: "bar"}
-//
-//	toks := []lexer.Token{openParen, closeParen}
-//	doAssert(toks, []lexer.Token{}, []lexer.Token{})
-//
-//	toks = []lexer.Token{openParen, foo, closeParen, bar}
-//	doAssert(toks, []lexer.Token{foo}, []lexer.Token{bar})
-//
-//	toks = []lexer.Token{openParen, foo, foo, closeParen, bar, bar}
-//	doAssert(toks, []lexer.Token{foo, foo}, []lexer.Token{bar, bar})
-//
-//	toks = []lexer.Token{openParen, foo, openParen, bar, closeParen, closeParen}
-//	doAssert(toks, []lexer.Token{foo, openParen, bar, closeParen}, []lexer.Token{})
-//
-//	toks = []lexer.Token{openParen, foo, openParen, bar, closeParen, bar, closeParen, foo}
-//	doAssert(toks, []lexer.Token{foo, openParen, bar, closeParen, bar}, []lexer.Token{foo})
-//}
-//
-//func assertParse(t *T, in []lexer.Token, expExpr Expr, expOut []lexer.Token) {
-//	expr, out, err := parse(in)
-//	require.Nil(t, err)
-//	assert.True(t, expExpr.equal(expr), "expr:%+v expExpr:%+v", expr, expExpr)
-//	assert.Equal(t, expOut, out, "out:%v expOut:%v", out, expOut)
-//}
-//
-//func TestParseSingle(t *T) {
-//	foo := lexer.Token{TokenType: lexer.Identifier, Val: "foo"}
-//	fooM := lexer.Token{TokenType: lexer.Identifier, Val: "%foo"}
-//	fooExpr := Expr{Actual: Identifier("foo")}
-//	fooMExpr := Expr{Actual: Macro("foo")}
-//
-//	toks := []lexer.Token{foo}
-//	assertParse(t, toks, fooExpr, []lexer.Token{})
-//
-//	toks = []lexer.Token{foo, foo}
-//	assertParse(t, toks, fooExpr, []lexer.Token{foo})
-//
-//	toks = []lexer.Token{openParen, foo, closeParen, foo}
-//	assertParse(t, toks, fooExpr, []lexer.Token{foo})
-//
-//	toks = []lexer.Token{openParen, openParen, foo, closeParen, closeParen, foo}
-//	assertParse(t, toks, fooExpr, []lexer.Token{foo})
-//
-//	toks = []lexer.Token{fooM, foo}
-//	assertParse(t, toks, fooMExpr, []lexer.Token{foo})
-//}
-//
-//func TestParseTuple(t *T) {
-//	tup := func(ee ...Expr) Expr {
-//		return Expr{Actual: Tuple(ee)}
-//	}
-//
-//	foo := lexer.Token{TokenType: lexer.Identifier, Val: "foo"}
-//	fooExpr := Expr{Actual: Identifier("foo")}
-//
-//	toks := []lexer.Token{foo, comma, foo}
-//	assertParse(t, toks, tup(fooExpr, fooExpr), []lexer.Token{})
-//
-//	toks = []lexer.Token{foo, comma, foo, foo}
-//	assertParse(t, toks, tup(fooExpr, fooExpr), []lexer.Token{foo})
-//
-//	toks = []lexer.Token{foo, comma, foo, comma, foo}
-//	assertParse(t, toks, tup(fooExpr, fooExpr, fooExpr), []lexer.Token{})
-//
-//	toks = []lexer.Token{foo, comma, foo, comma, foo, comma, foo}
-//	assertParse(t, toks, tup(fooExpr, fooExpr, fooExpr, fooExpr), []lexer.Token{})
-//
-//	toks = []lexer.Token{foo, comma, openParen, foo, comma, foo, closeParen, comma, foo}
-//	assertParse(t, toks, tup(fooExpr, tup(fooExpr, fooExpr), fooExpr), []lexer.Token{})
-//
-//	toks = []lexer.Token{foo, comma, openParen, foo, comma, foo, closeParen, comma, foo, foo}
-//	assertParse(t, toks, tup(fooExpr, tup(fooExpr, fooExpr), fooExpr), []lexer.Token{foo})
-//}
-//
-//func TestParseStatement(t *T) {
-//	stmt := func(in, to Expr) Expr {
-//		return Expr{Actual: Statement{In: in, To: to}}
-//	}
-//
-//	foo := lexer.Token{TokenType: lexer.Identifier, Val: "foo"}
-//	fooExpr := Expr{Actual: Identifier("foo")}
-//
-//	toks := []lexer.Token{foo, arrow, foo}
-//	assertParse(t, toks, stmt(fooExpr, fooExpr), []lexer.Token{})
-//
-//	toks = []lexer.Token{openParen, foo, arrow, foo, closeParen}
-//	assertParse(t, toks, stmt(fooExpr, fooExpr), []lexer.Token{})
-//
-//	toks = []lexer.Token{foo, arrow, openParen, foo, closeParen}
-//	assertParse(t, toks, stmt(fooExpr, fooExpr), []lexer.Token{})
-//
-//	toks = []lexer.Token{foo, arrow, foo}
-//	assertParse(t, toks, stmt(fooExpr, fooExpr), []lexer.Token{})
-//
-//	toks = []lexer.Token{foo, arrow, foo, foo}
-//	assertParse(t, toks, stmt(fooExpr, fooExpr), []lexer.Token{foo})
-//
-//	toks = []lexer.Token{foo, arrow, openParen, foo, closeParen, foo}
-//	assertParse(t, toks, stmt(fooExpr, fooExpr), []lexer.Token{foo})
-//
-//	toks = []lexer.Token{openParen, foo, closeParen, arrow, openParen, foo, closeParen, foo}
-//	assertParse(t, toks, stmt(fooExpr, fooExpr), []lexer.Token{foo})
-//
-//	fooTupExpr := Expr{Actual: Tuple{fooExpr, fooExpr}}
-//	toks = []lexer.Token{foo, arrow, openParen, foo, comma, foo, closeParen, foo}
-//	assertParse(t, toks, stmt(fooExpr, fooTupExpr), []lexer.Token{foo})
-//
-//	toks = []lexer.Token{foo, comma, foo, arrow, foo}
-//	assertParse(t, toks, stmt(fooTupExpr, fooExpr), []lexer.Token{})
-//
-//	toks = []lexer.Token{openParen, foo, comma, foo, closeParen, arrow, foo}
-//	assertParse(t, toks, stmt(fooTupExpr, fooExpr), []lexer.Token{})
-//}
-//
-//func TestParseBlock(t *T) {
-//	stmt := func(in, to Expr) Expr {
-//		return Expr{Actual: Statement{In: in, To: to}}
-//	}
-//	block := func(stmts ...Expr) Expr {
-//		return Expr{Actual: Block(stmts)}
-//	}
-//
-//	foo := lexer.Token{TokenType: lexer.Identifier, Val: "foo"}
-//	fooExpr := Expr{Actual: Identifier("foo")}
-//
-//	toks := []lexer.Token{openCurly, foo, arrow, foo, closeCurly}
-//	assertParse(t, toks, block(stmt(fooExpr, fooExpr)), []lexer.Token{})
-//
-//	toks = []lexer.Token{openCurly, foo, arrow, foo, closeCurly, foo}
-//	assertParse(t, toks, block(stmt(fooExpr, fooExpr)), []lexer.Token{foo})
-//
-//	toks = []lexer.Token{openCurly, foo, arrow, foo, openParen, foo, arrow, foo, closeParen, closeCurly, foo}
-//	assertParse(t, toks, block(stmt(fooExpr, fooExpr), stmt(fooExpr, fooExpr)), []lexer.Token{foo})
-//
-//	toks = []lexer.Token{openCurly, foo, arrow, foo, openParen, foo, arrow, foo, closeParen, closeCurly, foo}
-//	assertParse(t, toks, block(stmt(fooExpr, fooExpr), stmt(fooExpr, fooExpr)), []lexer.Token{foo})
-//}

expr/util.go

@@ -1,40 +0,0 @@
-package expr
-
-import (
-	"encoding/hex"
-	"fmt"
-	"math/rand"
-	"strings"
-)
-
-func randStr() string {
-	b := make([]byte, 16)
-	if _, err := rand.Read(b); err != nil {
-		panic(err)
-	}
-	return hex.EncodeToString(b)
-}
-
-func exprsJoin(ee []Expr) string {
-	strs := make([]string, len(ee))
-	for i := range ee {
-		strs[i] = fmt.Sprint(ee[i])
-	}
-	return strings.Join(strs, ", ")
-}
-
-func exprsEqual(ee1, ee2 []Expr) bool {
-	if len(ee1) != len(ee2) {
-		return false
-	}
-	for i := range ee1 {
-		if !exprEqual(ee1[i], ee2[i]) {
-			return false
-		}
-	}
-	return true
-}
-
-func panicf(msg string, args ...interface{}) {
-	panic(fmt.Sprintf(msg, args...))
-}

flake.lock

@@ -0,0 +1,26 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1696983906,
+        "narHash": "sha256-L7GyeErguS7Pg4h8nK0wGlcUTbfUMDu+HMf1UcyP72k=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "bd1cde45c77891214131cbbea5b1203e485a9d51",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "ref": "nixos-23.05",
+        "type": "indirect"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,44 @@
+{
+  description = "gotc development environment";
+
+  # Nixpkgs / NixOS version to use.
+  inputs.nixpkgs.url = "nixpkgs/nixos-23.05";
+
+  outputs = { self, nixpkgs }:
+    let
+
+      # to work with older version of flakes
+      lastModifiedDate = self.lastModifiedDate or self.lastModified or "19700101";
+
+      # Generate a user-friendly version number.
+      version = builtins.substring 0 8 lastModifiedDate;
+
+      # System types to support.
+      supportedSystems = [ "x86_64-linux" "x86_64-darwin" "aarch64-linux" "aarch64-darwin" ];
+
+      # Helper function to generate an attrset '{ x86_64-linux = f "x86_64-linux"; ... }'.
+      forAllSystems = nixpkgs.lib.genAttrs supportedSystems;
+
+      # Nixpkgs instantiated for supported system types.
+      nixpkgsFor = forAllSystems (system: import nixpkgs {
+        inherit system;
+      });
+
+    in
+    {
+
+      # Add dependencies that are only needed for development
+      devShells = forAllSystems (system:
+        let
+          pkgs = nixpkgsFor.${system};
+        in {
+          default = pkgs.mkShell {
+            buildInputs = [
+              pkgs.go
+              pkgs.gotools
+              pkgs.golangci-lint
+            ];
+          };
+        });
+    };
+}

gg/decoder.go

@@ -0,0 +1,297 @@
+package gg
+
+import (
+	"fmt"
+	"io"
+	"strconv"
+	"unicode"
+
+	. "code.betamike.com/mediocregopher/ginger/gg/grammar"
+	"code.betamike.com/mediocregopher/ginger/graph"
+	"golang.org/x/exp/slices"
+)
+
+var (
+	notNewline = RuneFunc(
+		"not-newline", func(r rune) bool { return r != '\n' },
+	)
+
+	comment = Prefixed(
+		Prefixed(Rune('*'), ZeroOrMore(notNewline)), Rune('\n'),
+	)
+
+	whitespace = ZeroOrMore(FirstOf(
+		Discard(RuneFunc("whitespace", unicode.IsSpace)),
+		Discard(comment),
+	))
+)
+
+func trimmed[T any](sym Symbol[T]) Symbol[T] {
+	sym = PrefixDiscarded(whitespace, sym)
+	sym = Suffixed(sym, whitespace)
+	return sym
+}
+
+func trimmedRune(r rune) Symbol[Located[rune]] {
+	return trimmed(Rune(r))
+}
+
+var (
+	digit = RuneFunc(
+		"digit", func(r rune) bool { return '0' <= r && r <= '9' },
+	)
+
+	positiveNumber = StringFromRunes(OneOrMore(digit))
+
+	negativeNumber = Reduction(
+		Rune('-'),
+		positiveNumber,
+		func(neg Located[rune], posNum Located[string]) Located[string] {
+			return Locate(neg.Location, string(neg.Value)+posNum.Value)
+		},
+	)
+
+	number = Named(
+		"number",
+		Mapping(
+			FirstOf(negativeNumber, positiveNumber),
+			func(str Located[string]) Located[Value] {
+				i, err := strconv.ParseInt(str.Value, 10, 64)
+				if err != nil {
+					panic(fmt.Errorf("parsing %q as int: %w", str, err))
+				}
+
+				return Locate(str.Location, Number(i))
+			},
+		),
+	)
+)
+
+var (
+	nameHead = FirstOf(
+		RuneFunc("letter", unicode.IsLetter),
+		RuneFunc("mark", unicode.IsMark),
+		Rune('!'),
+	)
+
+	nameTail = ZeroOrMore(FirstOf(nameHead, digit))
+
+	name = Named(
+		"name",
+		Reduction(
+			nameHead,
+			nameTail,
+			func(head Located[rune], tail []Located[rune]) Located[Value] {
+				name := make([]rune, 0, len(tail)+1)
+				name = append(name, head.Value)
+				for _, r := range tail {
+					name = append(name, r.Value)
+				}
+				return Locate(head.Location, Name(string(name)))
+			},
+		),
+	)
+)
+
+func openEdgeIntoValue(val Value, oe *OpenEdge) *OpenEdge {
+	switch {
+	case oe == nil:
+		return graph.ValueOut(None, val)
+	case !oe.EdgeValue().Valid:
+		return oe.WithEdgeValue(Some(val))
+	default:
+		return graph.TupleOut(Some(val), oe)
+	}
+}
+
+var graphSym, value = func() (
+	Symbol[Located[Value]], Symbol[Located[Value]],
+) {
+
+	type tupleState struct {
+		ins []*OpenEdge
+		oe  *OpenEdge
+	}
+
+	type graphState struct {
+		g  *Graph
+		oe *OpenEdge
+	}
+
+	var (
+		tupleEnd = Mapping(
+			trimmedRune(')'),
+			func(Located[rune]) tupleState {
+				// if ')', then map that to an empty state. This acts as a
+				// sentinel value to indicate "end of tuple".
+				return tupleState{}
+			},
+		)
+
+		graphEnd = Mapping(
+			trimmedRune('}'),
+			func(Located[rune]) graphState {
+				// if '}', then map that to an empty state. This acts as a
+				// sentinel value to indicate "end of graph".
+				return graphState{}
+			},
+		)
+	)
+
+	var (
+		// pre-define these, and then fill in the pointers after, in order to
+		// deal with recursive dependencies between them.
+		value = new(SymbolPtr[Located[Value]])
+
+		tuple                  = new(SymbolPtr[*OpenEdge])
+		tupleTail              = new(SymbolPtr[tupleState])
+		tupleOpenEdge          = new(SymbolPtr[tupleState])
+		tupleOpenEdgeTail      = new(SymbolPtr[tupleState])
+		tupleOpenEdgeValueTail = new(SymbolPtr[tupleState])
+
+		graphSym               = new(SymbolPtr[Located[Value]])
+		graphTail              = new(SymbolPtr[graphState])
+		graphOpenEdge          = new(SymbolPtr[graphState])
+		graphOpenEdgeTail      = new(SymbolPtr[graphState])
+		graphOpenEdgeValueTail = new(SymbolPtr[graphState])
+	)
+
+	tuple.Symbol = Named(
+		"tuple",
+		Reduction[Located[rune], tupleState, *OpenEdge](
+			trimmedRune('('),
+			tupleTail,
+			func(_ Located[rune], ts tupleState) *OpenEdge {
+				slices.Reverse(ts.ins)
+				return graph.TupleOut(None, ts.ins...)
+			},
+		),
+	)
+
+	tupleTail.Symbol = FirstOf(
+		tupleEnd,
+		Mapping[tupleState, tupleState](
+			tupleOpenEdge,
+			func(ts tupleState) tupleState {
+				ts.ins = append(ts.ins, ts.oe)
+				ts.oe = nil
+				return ts
+			},
+		),
+	)
+
+	tupleOpenEdge.Symbol = FirstOf(
+		Reduction[Located[Value], tupleState, tupleState](
+			value,
+			tupleOpenEdgeValueTail,
+			func(val Located[Value], ts tupleState) tupleState {
+				ts.oe = openEdgeIntoValue(val.Value, ts.oe)
+				return ts
+			},
+		),
+		Reduction[*OpenEdge, tupleState, tupleState](
+			tuple,
+			tupleOpenEdgeTail,
+			func(oe *OpenEdge, ts tupleState) tupleState {
+				ts.oe = oe
+				return ts
+			},
+		),
+	)
+
+	tupleOpenEdgeTail.Symbol = FirstOf(
+		tupleEnd,
+		Prefixed[Located[rune], tupleState](trimmedRune(','), tupleTail),
+	)
+
+	tupleOpenEdgeValueTail.Symbol = FirstOf[tupleState](
+		tupleOpenEdgeTail,
+		Prefixed[Located[rune], tupleState](trimmedRune('<'), tupleOpenEdge),
+	)
+
+	graphSym.Symbol = Named(
+		"graph",
+		Reduction[Located[rune], graphState, Located[Value]](
+			trimmedRune('{'),
+			graphTail,
+			func(r Located[rune], gs graphState) Located[Value] {
+				if gs.g == nil {
+					gs.g = new(Graph)
+				}
+
+				return Locate(r.Location, Value{Graph: gs.g})
+			},
+		),
+	)
+
+	graphTail.Symbol = FirstOf(
+		graphEnd,
+		Reduction(
+			name,
+			Prefixed[Located[rune], graphState](
+				trimmedRune('='), graphOpenEdge,
+			),
+			func(name Located[Value], gs graphState) graphState {
+				if gs.g == nil {
+					gs.g = new(Graph)
+				}
+
+				gs.g = gs.g.AddValueIn(name.Value, gs.oe)
+				gs.oe = nil
+				return gs
+			},
+		),
+	)
+
+	graphOpenEdge.Symbol = FirstOf(
+		Reduction[Located[Value], graphState, graphState](
+			value,
+			graphOpenEdgeValueTail,
+			func(val Located[Value], gs graphState) graphState {
+				gs.oe = openEdgeIntoValue(val.Value, gs.oe)
+				return gs
+			},
+		),
+		Reduction[*OpenEdge, graphState, graphState](
+			tuple,
+			graphOpenEdgeTail,
+			func(oe *OpenEdge, gs graphState) graphState {
+				gs.oe = oe
+				return gs
+			},
+		),
+	)
+
+	graphOpenEdgeTail.Symbol = FirstOf(
+		graphEnd,
+		Prefixed[Located[rune], graphState](trimmedRune(';'), graphTail),
+	)
+
+	graphOpenEdgeValueTail.Symbol = FirstOf[graphState](
+		graphOpenEdgeTail,
+		Prefixed[Located[rune], graphState](trimmedRune('<'), graphOpenEdge),
+	)
+
+	value.Symbol = trimmed(FirstOf[Located[Value]](name, number, graphSym))
+
+	return graphSym, value
+}()
+
+// Decoder reads Values off of an io.Reader, or return io.EOF.
+type Decoder interface {
+	Next() (Located[Value], error)
+}
+
+type decoder struct {
+	r Reader
+}
+
+// NewDecoder returns a Decoder which reads off the given io.Reader. The
+// io.Reader should not be read from after this call.
+func NewDecoder(r io.Reader) Decoder {
+	return &decoder{r: NewReader(r)}
+}
+
+func (d *decoder) Next() (Located[Value], error) {
+	return value.Decode(d.r)
+}

gg/decoder_test.go

@@ -0,0 +1,365 @@
+package gg
+
+import (
+	"bytes"
+	"strconv"
+	"testing"
+
+	. "code.betamike.com/mediocregopher/ginger/gg/grammar"
+	"code.betamike.com/mediocregopher/ginger/graph"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDecoder(t *testing.T) {
+	type test struct {
+		in     string
+		exp    Located[Value]
+		expErr string
+	}
+
+	runTests := func(
+		t *testing.T, name string, sym Symbol[Located[Value]], tests []test,
+	) {
+		t.Run(name, func(t *testing.T) {
+			for i, test := range tests {
+				t.Run(strconv.Itoa(i), func(t *testing.T) {
+					r := NewReader(bytes.NewBufferString(test.in))
+					got, err := sym.Decode(r)
+					if test.expErr != "" {
+						assert.Error(t, err)
+						assert.Equal(t, test.expErr, err.Error())
+					} else if assert.NoError(t, err) {
+						assert.True(t,
+							test.exp.Value.Equal(got.Value),
+							"\nexp:%v\ngot:%v", test.exp, got,
+						)
+						assert.Equal(t, test.exp.Location, got.Location)
+					}
+				})
+			}
+		})
+	}
+
+	expNum := func(row, col int, n int64) Located[Value] {
+		return Locate(Location{Row: row, Col: col}, Number(n))
+	}
+
+	runTests(t, "number", number, []test{
+		{in: `0`, exp: expNum(1, 1, 0)},
+		{in: `100`, exp: expNum(1, 1, 100)},
+		{in: `-100`, exp: expNum(1, 1, -100)},
+		{in: `0foo`, exp: expNum(1, 1, 0)},
+		{in: `100foo`, exp: expNum(1, 1, 100)},
+	})
+
+	expName := func(row, col int, name string) Located[Value] {
+		return Locate(Location{Row: row, Col: col}, Name(name))
+	}
+
+	expGraph := func(row, col int, g *Graph) Located[Value] {
+		return Locate(Location{Row: row, Col: col}, Value{Graph: g})
+	}
+
+	runTests(t, "name", name, []test{
+		{in: `a`, exp: expName(1, 1, "a")},
+		{in: `ab`, exp: expName(1, 1, "ab")},
+		{in: `ab2c`, exp: expName(1, 1, "ab2c")},
+		{in: `ab2c,`, exp: expName(1, 1, "ab2c")},
+		{in: `!ab2c,`, exp: expName(1, 1, "!ab2c")},
+	})
+
+	runTests(t, "graph", graphSym, []test{
+		{in: `{}`, exp: expGraph(1, 1, new(Graph))},
+		{in: `{`, expErr: `1:2: expected '}' or name`},
+		{in: `{a}`, expErr: `1:3: expected '='`},
+		{in: `{a=}`, expErr: `1:4: expected name or number or graph or tuple`},
+		{
+			in: `{foo=a}`,
+			exp: expGraph(
+				1, 1, new(Graph).
+					AddValueIn(Name("foo"), graph.ValueOut(None, Name("a"))),
+			),
+		},
+		{
+			in: `{ foo = a }`,
+			exp: expGraph(
+				1, 1, new(Graph).
+					AddValueIn(Name("foo"), graph.ValueOut(None, Name("a"))),
+			),
+		},
+		{in: `{1=a}`, expErr: `1:2: expected '}' or name`},
+		{in: `{foo=a ,}`, expErr: `1:8: expected '}' or ';' or '<'`},
+		{in: `{foo=a`, expErr: `1:7: expected '}' or ';' or '<'`},
+		{
+			in: `{foo=a<b}`,
+			exp: expGraph(
+				1, 1, new(Graph).
+					AddValueIn(
+						Name("foo"),
+						graph.ValueOut(Some(Name("a")), Name("b")),
+					),
+			),
+		},
+		{
+			in: `{foo=a< b <c}`,
+			exp: expGraph(
+				1, 1, new(Graph).
+					AddValueIn(
+						Name("foo"),
+						graph.TupleOut(
+							Some(Name("a")),
+							graph.ValueOut(
+								Some(Name("b")),
+								Name("c"),
+							),
+						),
+					),
+			),
+		},
+		{
+			in: `{foo =a<b<c<1 }`,
+			exp: expGraph(
+				1, 1, new(Graph).
+					AddValueIn(
+						Name("foo"),
+						graph.TupleOut(
+							Some(Name("a")),
+							graph.TupleOut(
+								Some(Name("b")),
+								graph.ValueOut(
+									Some(Name("c")),
+									Number(1),
+								),
+							),
+						),
+					),
+			),
+		},
+		{
+			in: `{foo=a<b ; }`,
+			exp: expGraph(
+				1, 1, new(Graph).
+					AddValueIn(
+						Name("foo"),
+						graph.ValueOut(
+							Some(Name("a")),
+							Name("b"),
+						),
+					),
+			),
+		},
+		{
+			in: `{foo=a<b;bar=c}`,
+			exp: expGraph(
+				1, 1, new(Graph).
+					AddValueIn(
+						Name("foo"),
+						graph.ValueOut(
+							Some(Name("a")),
+							Name("b"),
+						),
+					).
+					AddValueIn(
+						Name("bar"),
+						graph.ValueOut(None, Name("c")),
+					),
+			),
+		},
+		{
+			in: `{foo= a<{ baz=1 } ; bar=c}`,
+			exp: expGraph(
+				1, 1, new(Graph).
+					AddValueIn(
+						Name("foo"),
+						graph.ValueOut(
+							Some(Name("a")),
+							Value{Graph: new(Graph).AddValueIn(
+								Name("baz"),
+								graph.ValueOut(None, Number(1)),
+							)},
+						),
+					).
+					AddValueIn(
+						Name("bar"),
+						graph.ValueOut(None, Name("c")),
+					),
+			),
+		},
+		{
+			in: `{foo= {baz=1} <a; bar=c}`,
+			exp: expGraph(
+				1, 1, new(Graph).
+					AddValueIn(
+						Name("foo"),
+						graph.ValueOut(
+							Some(Value{Graph: new(Graph).AddValueIn(
+								Name("baz"),
+								graph.ValueOut(None, Number(1)),
+							)}),
+							Name("a"),
+						),
+					).
+					AddValueIn(
+						Name("bar"),
+						graph.ValueOut(None, Name("c")),
+					),
+			),
+		},
+	})
+
+	runTests(t, "tuple", graphSym, []test{
+		{
+			in: `{foo=(a)}`,
+			exp: expGraph(
+				1, 1, new(Graph).
+					AddValueIn(
+						Name("foo"),
+						graph.ValueOut(None, Name("a")),
+					),
+			),
+		},
+		{
+			in: `{foo=(a<b)}`,
+			exp: expGraph(
+				1, 1, new(Graph).
+					AddValueIn(
+						Name("foo"),
+						graph.ValueOut(
+							Some(Name("a")),
+							Name("b"),
+						),
+					),
+			),
+		},
+		{
+			in: `{foo=a<(b)}`,
+			exp: expGraph(
+				1, 1, new(Graph).
+					AddValueIn(
+						Name("foo"),
+						graph.ValueOut(
+							Some(Name("a")),
+							Name("b"),
+						),
+					),
+			),
+		},
+		{
+			in: `{foo=a<(b,c)}`,
+			exp: expGraph(
+				1, 1, new(Graph).
+					AddValueIn(
+						Name("foo"),
+						graph.TupleOut(
+							Some(Name("a")),
+							graph.ValueOut(None, Name("b")),
+							graph.ValueOut(None, Name("c")),
+						),
+					),
+			),
+		},
+		{
+			in: `{foo=a<(b<c)}`,
+			exp: expGraph(
+				1, 1, new(Graph).
+					AddValueIn(
+						Name("foo"),
+						graph.TupleOut(
+							Some(Name("a")),
+							graph.TupleOut(
+								Some(Name("b")),
+								graph.ValueOut(None, Name("c")),
+							),
+						),
+					),
+			),
+		},
+		{
+			in: `{foo=a<(b<(c))}`,
+			exp: expGraph(
+				1, 1, new(Graph).
+					AddValueIn(
+						Name("foo"),
+						graph.TupleOut(
+							Some(Name("a")),
+							graph.TupleOut(
+								Some(Name("b")),
+								graph.ValueOut(None, Name("c")),
+							),
+						),
+					),
+			),
+		},
+		{
+			in: `{foo=a<(b<(c,d<1))}`,
+			exp: expGraph(
+				1, 1, new(Graph).
+					AddValueIn(
+						Name("foo"),
+						graph.TupleOut(
+							Some(Name("a")),
+							graph.TupleOut(
+								Some(Name("b")),
+								graph.ValueOut(None, Name("c")),
+								graph.ValueOut(
+									Some(Name("d")),
+									Number(1),
+								),
+							),
+						),
+					),
+			),
+		},
+		{
+			in: `{foo=a<(b<( ( (c) ) ))}`,
+			exp: expGraph(
+				1, 1, new(Graph).
+					AddValueIn(
+						Name("foo"),
+						graph.TupleOut(
+							Some(Name("a")),
+							graph.TupleOut(
+								Some(Name("b")),
+								graph.ValueOut(None, Name("c")),
+							),
+						),
+					),
+			),
+		},
+	})
+
+	runTests(t, "comment", graphSym, []test{
+		{
+			in:  "*\n{}",
+			exp: expGraph(2, 1, new(Graph)),
+		},
+		{
+			in:  "* ignore me!\n{}",
+			exp: expGraph(2, 1, new(Graph)),
+		},
+		{
+			in:  "{* ignore me!\n}",
+			exp: expGraph(1, 1, new(Graph)),
+		},
+		{
+			in: "{foo* ignore me!\n  =  a}",
+			exp: expGraph(
+				1, 1, new(Graph).
+					AddValueIn(
+						Name("foo"),
+						graph.ValueOut(None, Name("a")),
+					),
+			),
+		},
+		{
+			in: "{foo  =  a* ignore me!\n}",
+			exp: expGraph(
+				1, 1, new(Graph).
+					AddValueIn(
+						Name("foo"),
+						graph.ValueOut(None, Name("a")),
+					),
+			),
+		},
+	})
+}

gg/gg.bnf

@@ -0,0 +1,25 @@
+<digit>           ::= "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"
+<positive-number> ::= <digit>+
+<negative-number> ::= "-" <positive-number>
+<number>          ::= <negative-number> | <positive-number>
+
+<name-head> ::= <letter> | <mark> | "!"
+<name-tail> ::= <name-head> | <digit>
+<name> ::= <name-head> <name-tail>*
+
+<tuple>                      ::= "(" <tuple-tail>
+<tuple-tail>                 ::= ")" | <tuple-open-edge>
+<tuple-open-edge>            ::= <value> <tuple-open-edge-value-tail>
+                               | <tuple> <tuple-open-edge-tail>
+<tuple-open-edge-tail>       ::= ")" | "," <tuple-tail>
+<tuple-open-edge-value-tail> ::= <tuple-open-edge-tail> | "<" <tuple-open-edge>
+
+<graph>                      ::= "{" <graph-tail>
+<graph-tail>                 ::= "}" | <name> "=" <graph-open-edge>
+<graph-open-edge>            ::= <value> <graph-open-edge-value-tail>
+                               | <tuple> <graph-open-edge-tail>
+<graph-open-edge-tail>       ::= "}" | ";" <graph-tail>
+<graph-open-edge-value-tail> ::= <graph-open-edge-tail> | "<" <graph-open-edge>
+
+<value> ::= <name> | <number> | <graph>
+<gg>    ::= <eof> | <value> <gg>

gg/gg.go

@@ -1,554 +1,114 @@
-// Package gg implements ginger graph creation, traversal, and (de)serialization
+// Package gg implements graph serialization to/from the gg text format.
 package gg
 
 import (
-	"crypto/rand"
-	"encoding/hex"
 	"fmt"
-	"strings"
+
+	"code.betamike.com/mediocregopher/ginger/graph"
 )
 
-// Value wraps a go value in a way such that it will be uniquely identified
-// within any Graph and between Graphs. Use NewValue to create a Value instance.
-// You can create an instance manually as long as ID is globally unique.
+// Type aliases for convenience
+type (
+	Graph    = graph.Graph[OptionalValue, Value]
+	OpenEdge = graph.OpenEdge[OptionalValue, Value]
+)
+
+// Value represents a value which can be serialized by the gg text format.
 type Value struct {
-	ID string
-	V  interface{}
+	// Only one of these fields may be set
+	Name   *string
+	Number *int64
+	Graph  *Graph
 }
 
-// NewValue returns a Value instance wrapping any go value. The Value returned
-// will be independent of the passed in go value. So if the same go value is
-// passed in twice then the two returned Value instances will be treated as
-// being different values by Graph.
-func NewValue(V interface{}) Value {
-	b := make([]byte, 8)
-	if _, err := rand.Read(b); err != nil {
-		panic(err)
-	}
-	return Value{
-		ID: hex.EncodeToString(b),
-		V:  V,
-	}
+// Name returns a name Value.
+func Name(name string) Value {
+	return Value{Name: &name}
 }
 
-// VertexType enumerates the different possible vertex types
-type VertexType string
-
-const (
-	// ValueVertex is a Vertex which contains exactly one value and has at least
-	// one edge (either input or output)
-	ValueVertex VertexType = "value"
-
-	// JunctionVertex is a Vertex which contains two or more in edges and
-	// exactly one out edge
-	JunctionVertex VertexType = "junction"
-)
-
-// Edge is a uni-directional connection between two vertices with an attribute
-// value
-type Edge struct {
-	From  *Vertex
-	Value Value
-	To    *Vertex
+// Number returns a number Value.
+func Number(n int64) Value {
+	return Value{Number: &n}
 }
 
-// Vertex is a vertex in a Graph. No fields should be modified directly, only
-// through method calls
-type Vertex struct {
-	ID string
-	VertexType
-	Value   Value // Value is valid if-and-only-if VertexType is ValueVertex
-	In, Out []Edge
-}
-
-////////////////////////////////////////////////////////////////////////////////
-
-// OpenEdge is an un-realized Edge which can't be used for anything except
-// constructing graphs. It has no meaning on its own.
-type OpenEdge struct {
-	// fromV will be the source vertex as-if the vertex (and any sub-vertices of
-	// it) doesn't already exist in the graph. If it or it's sub-vertices does
-	// already that will need to be taken into account when persisting into the
-	// graph
-	fromV vertex
-	val   Value
-}
-
-func (oe OpenEdge) id() string {
-	return fmt.Sprintf("(%s,%s)", oe.fromV.id, oe.val.ID)
-}
-
-// vertex is a representation of a vertex in the graph. Each Graph contains a
-// set of all the Value vertex instances it knows about. Each of these contains
-// all the input OpenEdges which are known for it. So you can think of these
-// "top-level" Value vertex instances as root nodes in a tree, and each OpenEdge
-// as a branch.
+// Equal returns true if the passed in Value is equivalent, ignoring the
+// LexerToken on either Value.
 //
-// If a OpenEdge contains a fromV which is a Value that vertex won't have its in
-// slice populated no matter what. If fromV is a Junction it will be populated,
-// with any sub-Value's not being populated and so-on recursively
-//
-// When a view is constructed in makeView these Value instances are deduplicated
-// and the top-level one's in value is used to properly connect it.
-type vertex struct {
-	id string
-	VertexType
-	val Value
-	in  []OpenEdge
-}
+// Will panic if the passed in v2 is not a Value from this package.
+func (v Value) Equal(v2g graph.Value) bool {
 
-func (v vertex) cp() vertex {
-	cp := v
-	cp.in = make([]OpenEdge, len(v.in))
-	copy(cp.in, v.in)
-	return cp
-}
+	v2 := v2g.(Value)
 
-func (v vertex) hasOpenEdge(oe OpenEdge) bool {
-	oeID := oe.id()
-	for _, in := range v.in {
-		if in.id() == oeID {
-			return true
-		}
-	}
-	return false
-}
+	switch {
 
-func (v vertex) cpAndDelOpenEdge(oe OpenEdge) (vertex, bool) {
-	oeID := oe.id()
-	for i, in := range v.in {
-		if in.id() == oeID {
-			v = v.cp()
-			v.in = append(v.in[:i], v.in[i+1:]...)
-			return v, true
-		}
-	}
-	return v, false
-}
+	case v.Name != nil && v2.Name != nil && *v.Name == *v2.Name:
+		return true
 
-// Graph is a wrapper around a set of connected Vertices
-type Graph struct {
-	vM map[string]vertex // only contains value vertices
+	case v.Number != nil && v2.Number != nil && *v.Number == *v2.Number:
+		return true
 
-	// generated by makeView on-demand
-	byVal map[string]*Vertex
-	all   map[string]*Vertex
-}
+	case v.Graph != nil && v2.Graph != nil && v.Graph.Equal(v2.Graph):
+		return true
 
-// Null is the root empty graph, and is the base off which all graphs are built
-var Null = &Graph{
-	vM:    map[string]vertex{},
-	byVal: map[string]*Vertex{},
-	all:   map[string]*Vertex{},
-}
-
-// this does _not_ copy the view, as it's assumed the only reason to copy a
-// graph is to modify it anyway
-func (g *Graph) cp() *Graph {
-	cp := &Graph{
-		vM: make(map[string]vertex, len(g.vM)),
-	}
-	for vID, v := range g.vM {
-		cp.vM[vID] = v
-	}
-	return cp
-}
-
-////////////////////////////////////////////////////////////////////////////////
-// Graph creation
-
-func mkVertex(typ VertexType, val Value, ins ...OpenEdge) vertex {
-	v := vertex{VertexType: typ, in: ins}
-	switch typ {
-	case ValueVertex:
-		v.id = val.ID
-		v.val = val
-	case JunctionVertex:
-		inIDs := make([]string, len(ins))
-		for i := range ins {
-			inIDs[i] = ins[i].id()
-		}
-		v.id = "[" + strings.Join(inIDs, ",") + "]"
 	default:
-		panic(fmt.Sprintf("unknown vertex type %q", typ))
-	}
-	return v
-}
-
-// ValueOut creates a OpenEdge which, when used to construct a Graph, represents
-// an edge (with edgeVal attached to it) coming from the ValueVertex containing
-// val.
-//
-// When constructing Graphs, Value vertices are de-duplicated on their Value. So
-// multiple ValueOut OpenEdges constructed with the same val will be leaving the
-// same Vertex instance in the constructed Graph.
-func ValueOut(val, edgeVal Value) OpenEdge {
-	return OpenEdge{fromV: mkVertex(ValueVertex, val), val: edgeVal}
-}
-
-// JunctionOut creates a OpenEdge which, when used to construct a Graph,
-// represents an edge (with edgeVal attached to it) coming from the
-// JunctionVertex comprised of the given ordered-set of input edges.
-//
-// When constructing Graphs Junction vertices are de-duplicated on their input
-// edges. So multiple Junction OpenEdges constructed with the same set of input
-// edges will be leaving the same Junction instance in the constructed Graph.
-func JunctionOut(ins []OpenEdge, edgeVal Value) OpenEdge {
-	return OpenEdge{
-		fromV: mkVertex(JunctionVertex, Value{}, ins...),
-		val:   edgeVal,
-	}
-}
-
-// AddValueIn takes a OpenEdge and connects it to the Value Vertex containing
-// val, returning the new Graph which reflects that connection. Any Vertices
-// referenced within toe OpenEdge which do not yet exist in the Graph will also
-// be created in this step.
-func (g *Graph) AddValueIn(oe OpenEdge, val Value) *Graph {
-	to := mkVertex(ValueVertex, val)
-	toID := to.id
-
-	// if to is already in the graph, pull it out, as it might have existing in
-	// edges we want to keep
-	if exTo, ok := g.vM[toID]; ok {
-		to = exTo
-	}
-
-	// if the incoming edge already exists in to then there's nothing to do
-	if to.hasOpenEdge(oe) {
-		return g
-	}
-
-	to = to.cp()
-	to.in = append(to.in, oe)
-	g = g.cp()
-
-	// starting with to (which we always overwrite) go through vM and
-	// recursively add in any vertices which aren't already there
-	var persist func(vertex)
-	persist = func(v vertex) {
-		if v.VertexType == ValueVertex {
-			vID := v.id
-			if _, ok := g.vM[vID]; !ok {
-				g.vM[vID] = v
-			}
-		} else {
-			for _, e := range v.in {
-				persist(e.fromV)
-			}
-		}
-	}
-	delete(g.vM, toID)
-	persist(to)
-	for _, e := range to.in {
-		persist(e.fromV)
-	}
-
-	return g
-}
-
-// DelValueIn takes a OpenEdge and disconnects it from the Value Vertex
-// containing val, returning the new Graph which reflects the disconnection. If
-// the Value Vertex doesn't exist within the graph, or it doesn't have the given
-// OpenEdge, no changes are made. Any vertices referenced by toe OpenEdge for
-// which that edge is their only outgoing edge will be removed from the Graph.
-func (g *Graph) DelValueIn(oe OpenEdge, val Value) *Graph {
-	to := mkVertex(ValueVertex, val)
-	toID := to.id
-
-	// pull to out of the graph. if it's not there then bail
-	var ok bool
-	if to, ok = g.vM[toID]; !ok {
-		return g
-	}
-
-	// get new copy of to without the half-edge, or return if the half-edge
-	// wasn't even in to
-	to, ok = to.cpAndDelOpenEdge(oe)
-	if !ok {
-		return g
-	}
-	g = g.cp()
-	g.vM[toID] = to
-
-	// connectedTo returns whether the vertex has any connections with the
-	// vertex of the given id, descending recursively
-	var connectedTo func(string, vertex) bool
-	connectedTo = func(vID string, curr vertex) bool {
-		for _, in := range curr.in {
-			if in.fromV.VertexType == ValueVertex && in.fromV.id == vID {
-				return true
-			} else if in.fromV.VertexType == JunctionVertex && connectedTo(vID, in.fromV) {
-				return true
-			}
-		}
 		return false
 	}
+}
 
-	// isOrphaned returns whether the given vertex has any connections to other
-	// nodes in the graph
-	isOrphaned := func(v vertex) bool {
-		vID := v.id
-		if v, ok := g.vM[vID]; ok && len(v.in) > 0 {
-			return false
-		}
-		for vID2, v2 := range g.vM {
-			if vID2 == vID {
-				continue
-			} else if connectedTo(vID, v2) {
-				return false
-			}
-		}
+func (v Value) String() string {
+
+	switch {
+
+	case v.Name != nil:
+		return *v.Name
+
+	case v.Number != nil:
+		return fmt.Sprint(*v.Number)
+
+	case v.Graph != nil:
+		return v.Graph.String()
+
+	default:
+		panic("no fields set on Value")
+	}
+}
+
+// OptionalValue is a Value which may be unset. This is used for edge values,
+// since edges might not have a value.
+type OptionalValue struct {
+	Value
+	Valid bool
+}
+
+// None is the zero OptionalValue (hello rustaceans).
+var None OptionalValue
+
+// Some wraps a Value to be an OptionalValue.
+func Some(v Value) OptionalValue {
+	return OptionalValue{Valid: true, Value: v}
+}
+
+func (v OptionalValue) String() string {
+	if !v.Valid {
+		return "<none>"
+	}
+	return v.Value.String()
+}
+
+func (v OptionalValue) Equal(v2g graph.Value) bool {
+	var v2 OptionalValue
+
+	if v2Val, ok := v2g.(Value); ok {
+		v2 = Some(v2Val)
+	} else {
+		v2 = v2g.(OptionalValue)
+	}
+
+	if v.Valid != v2.Valid {
+		return false
+	} else if !v.Valid {
 		return true
 	}
 
-	// if to is orphaned get rid of it
-	if isOrphaned(to) {
-		delete(g.vM, toID)
-	}
-
-	// rmOrphaned descends down the given OpenEdge and removes any Value
-	// Vertices referenced in it which are now orphaned
-	var rmOrphaned func(OpenEdge)
-	rmOrphaned = func(oe OpenEdge) {
-		if oe.fromV.VertexType == ValueVertex && isOrphaned(oe.fromV) {
-			delete(g.vM, oe.fromV.id)
-		} else if oe.fromV.VertexType == JunctionVertex {
-			for _, juncOe := range oe.fromV.in {
-				rmOrphaned(juncOe)
-			}
-		}
-	}
-	rmOrphaned(oe)
-
-	return g
-}
-
-// Union takes in another Graph and returns a new one which is the union of the
-// two. Value vertices which are shared between the two will be merged so that
-// the new vertex has the input edges of both.
-//
-// TODO it bothers me that the opposite of Disjoin is Union and not "Join"
-func (g *Graph) Union(g2 *Graph) *Graph {
-	g = g.cp()
-	for vID, v2 := range g2.vM {
-		v, ok := g.vM[vID]
-		if !ok {
-			v = v2
-		} else {
-			for _, v2e := range v2.in {
-				if !v.hasOpenEdge(v2e) {
-					v.in = append(v.in, v2e)
-				}
-			}
-		}
-		g.vM[vID] = v
-	}
-	return g
-}
-
-// Disjoin splits the Graph into as many independently connected Graphs as it
-// contains. Each Graph returned will have vertices connected only within itself
-// and not across to the other Graphs, and the Union of all returned Graphs will
-// be the original again.
-//
-// The order of the Graphs returned is not deterministic.
-//
-// Null.Disjoin() returns empty slice.
-func (g *Graph) Disjoin() []*Graph {
-	m := map[string]*Graph{}    // maps each id to the Graph it belongs to
-	mG := map[*Graph]struct{}{} // tracks unique Graphs created
-
-	var connectedTo func(vertex) *Graph
-	connectedTo = func(v vertex) *Graph {
-		if v.VertexType == ValueVertex {
-			if g := m[v.id]; g != nil {
-				return g
-			}
-		}
-		for _, oe := range v.in {
-			if g := connectedTo(oe.fromV); g != nil {
-				return g
-			}
-		}
-		return nil
-	}
-
-	// used upon finding out that previously-thought-to-be disconnected vertices
-	// aren't. Merges the two graphs they're connected into together into one
-	// and updates all state internal to this function accordingly.
-	rejoin := func(gDst, gSrc *Graph) {
-		for id, v := range gSrc.vM {
-			gDst.vM[id] = v
-			m[id] = gDst
-		}
-		delete(mG, gSrc)
-	}
-
-	var connectTo func(vertex, *Graph)
-	connectTo = func(v vertex, g *Graph) {
-		if v.VertexType == ValueVertex {
-			if g2, ok := m[v.id]; ok && g != g2 {
-				rejoin(g, g2)
-			}
-			m[v.id] = g
-		}
-		for _, oe := range v.in {
-			connectTo(oe.fromV, g)
-		}
-	}
-
-	for id, v := range g.vM {
-		gV := connectedTo(v)
-
-		// if gV is nil it means this vertex is part of a new Graph which
-		// nothing else has been connected to yet.
-		if gV == nil {
-			gV = Null.cp()
-			mG[gV] = struct{}{}
-		}
-		gV.vM[id] = v
-
-		// do this no matter what, because we want to descend in to the in edges
-		// and mark all of those as being part of this graph too
-		connectTo(v, gV)
-	}
-
-	gg := make([]*Graph, 0, len(mG))
-	for g := range mG {
-		gg = append(gg, g)
-	}
-	return gg
-}
-
-////////////////////////////////////////////////////////////////////////////////
-// Graph traversal
-
-func (g *Graph) makeView() {
-	if g.byVal != nil {
-		return
-	}
-
-	g.byVal = make(map[string]*Vertex, len(g.vM))
-	g.all = map[string]*Vertex{}
-
-	var getV func(vertex, bool) *Vertex
-	getV = func(v vertex, top bool) *Vertex {
-		V, ok := g.all[v.id]
-		if !ok {
-			V = &Vertex{ID: v.id, VertexType: v.VertexType, Value: v.val}
-			g.all[v.id] = V
-		}
-
-		// we can be sure all Value vertices will be called with top==true at
-		// some point, so we only need to descend into the input edges if:
-		// * top is true
-		// * this is a junction's first time being gotten
-		if !top && (ok || v.VertexType != JunctionVertex) {
-			return V
-		}
-
-		V.In = make([]Edge, 0, len(v.in))
-		for i := range v.in {
-			fromV := getV(v.in[i].fromV, false)
-			e := Edge{From: fromV, Value: v.in[i].val, To: V}
-			fromV.Out = append(fromV.Out, e)
-			V.In = append(V.In, e)
-		}
-
-		if v.VertexType == ValueVertex {
-			g.byVal[v.val.ID] = V
-		}
-
-		return V
-	}
-
-	for _, v := range g.vM {
-		getV(v, true)
-	}
-}
-
-// ValueVertex returns the Value Vertex for the given value. If the Graph
-// doesn't contain a vertex for the value then nil is returned
-func (g *Graph) ValueVertex(val Value) *Vertex {
-	g.makeView()
-	return g.byVal[val.ID]
-}
-
-// ValueVertices returns all Value Vertices in the Graph
-func (g *Graph) ValueVertices() []*Vertex {
-	g.makeView()
-	vv := make([]*Vertex, 0, len(g.byVal))
-	for _, v := range g.byVal {
-		vv = append(vv, v)
-	}
-	return vv
-}
-
-// Equal returns whether or not the two Graphs are equivalent in value
-func Equal(g1, g2 *Graph) bool {
-	if len(g1.vM) != len(g2.vM) {
-		return false
-	}
-	for v1ID, v1 := range g1.vM {
-		v2, ok := g2.vM[v1ID]
-		if !ok {
-			return false
-		}
-
-		// since the vertices are values we must make sure their input sets are
-		// the same (which is tricky since they're unordered, unlike a
-		// junction's)
-		if len(v1.in) != len(v2.in) {
-			return false
-		}
-		for _, in := range v1.in {
-			if !v2.hasOpenEdge(in) {
-				return false
-			}
-		}
-	}
-	return true
-}
-
-// TODO Walk, but by edge
-// TODO Walk, but without end. AKA FSM
-
-// Iter will iterate through the Graph's vertices, calling the callback on every
-// Vertex in the Graph once. The vertex order used is non-deterministic.  If the
-// callback returns false the iteration is stopped.
-func (g *Graph) Iter(callback func(*Vertex) bool) {
-	g.makeView()
-	if len(g.byVal) == 0 {
-		return
-	}
-
-	seen := make(map[*Vertex]bool, len(g.byVal))
-	var innerWalk func(*Vertex) bool
-	innerWalk = func(v *Vertex) bool {
-		if seen[v] {
-			return true
-		} else if !callback(v) {
-			return false
-		}
-		seen[v] = true
-		for _, e := range v.In {
-			if !innerWalk(e.From) {
-				return false
-			}
-		}
-		return true
-	}
-
-	for _, v := range g.byVal {
-		if !innerWalk(v) {
-			return
-		}
-	}
-}
-
-// ByID returns all vertices indexed by their ID field
-func (g *Graph) ByID() map[string]*Vertex {
-	g.makeView()
-	return g.all
+	return v.Value.Equal(v2.Value)
 }

gg/gg_test.go

@@ -1,665 +0,0 @@
-package gg
-
-import (
-	"fmt"
-	"sort"
-	"strings"
-	. "testing"
-
-	"github.com/stretchr/testify/assert"
-)
-
-func edge(val Value, from *Vertex) Edge {
-	return Edge{Value: val, From: from}
-}
-
-func value(val Value, in ...Edge) *Vertex {
-	return &Vertex{
-		VertexType: ValueVertex,
-		Value:      val,
-		In:         in,
-	}
-}
-
-func junction(val Value, in ...Edge) Edge {
-	return Edge{
-		From: &Vertex{
-			VertexType: JunctionVertex,
-			In:         in,
-		},
-		Value: val,
-	}
-}
-
-func assertVertexEqual(t *T, exp, got *Vertex, msgAndArgs ...interface{}) bool {
-	var assertInner func(*Vertex, *Vertex, map[*Vertex]bool) bool
-	assertInner = func(exp, got *Vertex, m map[*Vertex]bool) bool {
-		// if got is already in m then we've already looked at it
-		if m[got] {
-			return true
-		}
-		m[got] = true
-
-		assert.Equal(t, exp.VertexType, got.VertexType, msgAndArgs...)
-		assert.Equal(t, exp.Value, got.Value, msgAndArgs...)
-		if !assert.Len(t, got.In, len(exp.In), msgAndArgs...) {
-			return false
-		}
-		for i := range exp.In {
-			assertInner(exp.In[i].From, got.In[i].From, m)
-			assert.Equal(t, exp.In[i].Value, got.In[i].Value, msgAndArgs...)
-			assert.Equal(t, got, got.In[i].To)
-			assert.Contains(t, got.In[i].From.Out, got.In[i])
-		}
-		return true
-
-	}
-	return assertInner(exp, got, map[*Vertex]bool{})
-}
-
-func assertIter(t *T, expVals, expJuncs int, g *Graph, msgAndArgs ...interface{}) {
-	seen := map[*Vertex]bool{}
-	var gotVals, gotJuncs int
-	g.Iter(func(v *Vertex) bool {
-		assert.NotContains(t, seen, v, msgAndArgs...)
-		seen[v] = true
-		if v.VertexType == ValueVertex {
-			gotVals++
-		} else {
-			gotJuncs++
-		}
-		return true
-	})
-	assert.Equal(t, expVals, gotVals, msgAndArgs...)
-	assert.Equal(t, expJuncs, gotJuncs, msgAndArgs...)
-}
-
-type graphTest struct {
-	name              string
-	out               func() *Graph
-	exp               []*Vertex
-	numVals, numJuncs int
-}
-
-func mkTest(name string, out func() *Graph, numVals, numJuncs int, exp ...*Vertex) graphTest {
-	return graphTest{
-		name:    name,
-		out:     out,
-		exp:     exp,
-		numVals: numVals, numJuncs: numJuncs,
-	}
-}
-
-func TestGraph(t *T) {
-	var (
-		v0  = NewValue("v0")
-		v1  = NewValue("v1")
-		v2  = NewValue("v2")
-		v3  = NewValue("v3")
-		e0  = NewValue("e0")
-		e00 = NewValue("e00")
-		e01 = NewValue("e01")
-		e1  = NewValue("e1")
-		e10 = NewValue("e10")
-		e11 = NewValue("e11")
-		e2  = NewValue("e2")
-		e20 = NewValue("e20")
-		e21 = NewValue("e21")
-		ej0 = NewValue("ej0")
-		ej1 = NewValue("ej1")
-		ej2 = NewValue("ej2")
-	)
-	tests := []graphTest{
-		mkTest(
-			"values-basic",
-			func() *Graph {
-				return Null.AddValueIn(ValueOut(v0, e0), v1)
-			},
-			2, 0,
-			value(v0),
-			value(v1, edge(e0, value(v0))),
-		),
-
-		mkTest(
-			"values-2edges",
-			func() *Graph {
-				g0 := Null.AddValueIn(ValueOut(v0, e0), v2)
-				return g0.AddValueIn(ValueOut(v1, e1), v2)
-			},
-			3, 0,
-			value(v0),
-			value(v1),
-			value(v2,
-				edge(e0, value(v0)),
-				edge(e1, value(v1)),
-			),
-		),
-
-		mkTest(
-			"values-separate",
-			func() *Graph {
-				g0 := Null.AddValueIn(ValueOut(v0, e0), v1)
-				return g0.AddValueIn(ValueOut(v2, e2), v3)
-			},
-			4, 0,
-			value(v0),
-			value(v1, edge(e0, value(v0))),
-			value(v2),
-			value(v3, edge(e2, value(v2))),
-		),
-
-		mkTest(
-			"values-circular",
-			func() *Graph {
-				return Null.AddValueIn(ValueOut(v0, e0), v0)
-			},
-			1, 0,
-			value(v0, edge(e0, value(v0))),
-		),
-
-		mkTest(
-			"values-circular2",
-			func() *Graph {
-				g0 := Null.AddValueIn(ValueOut(v0, e0), v1)
-				return g0.AddValueIn(ValueOut(v1, e1), v0)
-			},
-			2, 0,
-			value(v0, edge(e1, value(v1, edge(e0, value(v0))))),
-			value(v1, edge(e0, value(v0, edge(e1, value(v1))))),
-		),
-
-		mkTest(
-			"values-circular3",
-			func() *Graph {
-				g0 := Null.AddValueIn(ValueOut(v0, e0), v1)
-				g1 := g0.AddValueIn(ValueOut(v1, e1), v2)
-				return g1.AddValueIn(ValueOut(v2, e2), v1)
-			},
-			3, 0,
-			value(v0),
-			value(v1,
-				edge(e0, value(v0)),
-				edge(e2, value(v2, edge(e1, value(v1)))),
-			),
-			value(v2, edge(e1, value(v1,
-				edge(e0, value(v0)),
-				edge(e2, value(v2)),
-			))),
-		),
-
-		mkTest(
-			"junction-basic",
-			func() *Graph {
-				e0 := ValueOut(v0, e0)
-				e1 := ValueOut(v1, e1)
-				ej0 := JunctionOut([]OpenEdge{e0, e1}, ej0)
-				return Null.AddValueIn(ej0, v2)
-			},
-			3, 1,
-			value(v0), value(v1),
-			value(v2, junction(ej0,
-				edge(e0, value(v0)),
-				edge(e1, value(v1)),
-			)),
-		),
-
-		mkTest(
-			"junction-basic2",
-			func() *Graph {
-				e00 := ValueOut(v0, e00)
-				e10 := ValueOut(v1, e10)
-				ej0 := JunctionOut([]OpenEdge{e00, e10}, ej0)
-				e01 := ValueOut(v0, e01)
-				e11 := ValueOut(v1, e11)
-				ej1 := JunctionOut([]OpenEdge{e01, e11}, ej1)
-				ej2 := JunctionOut([]OpenEdge{ej0, ej1}, ej2)
-				return Null.AddValueIn(ej2, v2)
-			},
-			3, 3,
-			value(v0), value(v1),
-			value(v2, junction(ej2,
-				junction(ej0,
-					edge(e00, value(v0)),
-					edge(e10, value(v1)),
-				),
-				junction(ej1,
-					edge(e01, value(v0)),
-					edge(e11, value(v1)),
-				),
-			)),
-		),
-
-		mkTest(
-			"junction-circular",
-			func() *Graph {
-				e0 := ValueOut(v0, e0)
-				e1 := ValueOut(v1, e1)
-				ej0 := JunctionOut([]OpenEdge{e0, e1}, ej0)
-				g0 := Null.AddValueIn(ej0, v2)
-				e20 := ValueOut(v2, e20)
-				g1 := g0.AddValueIn(e20, v0)
-				e21 := ValueOut(v2, e21)
-				return g1.AddValueIn(e21, v1)
-			},
-			3, 1,
-			value(v0, edge(e20, value(v2, junction(ej0,
-				edge(e0, value(v0)),
-				edge(e1, value(v1, edge(e21, value(v2)))),
-			)))),
-			value(v1, edge(e21, value(v2, junction(ej0,
-				edge(e0, value(v0, edge(e20, value(v2)))),
-				edge(e1, value(v1)),
-			)))),
-			value(v2, junction(ej0,
-				edge(e0, value(v0, edge(e20, value(v2)))),
-				edge(e1, value(v1, edge(e21, value(v2)))),
-			)),
-		),
-	}
-
-	for i := range tests {
-		t.Logf("test[%d]:%q", i, tests[i].name)
-		out := tests[i].out()
-		for j, exp := range tests[i].exp {
-			msgAndArgs := []interface{}{
-				"tests[%d].name:%q exp[%d].val:%q",
-				i, tests[i].name, j, exp.Value.V.(string),
-			}
-			v := out.ValueVertex(exp.Value)
-			if !assert.NotNil(t, v, msgAndArgs...) {
-				continue
-			}
-			assertVertexEqual(t, exp, v, msgAndArgs...)
-		}
-
-		msgAndArgs := []interface{}{
-			"tests[%d].name:%q",
-			i, tests[i].name,
-		}
-
-		// sanity check that graphs are equal to themselves
-		assert.True(t, Equal(out, out), msgAndArgs...)
-
-		// test the Iter method in here too
-		assertIter(t, tests[i].numVals, tests[i].numJuncs, out, msgAndArgs...)
-	}
-}
-
-func TestGraphImmutability(t *T) {
-	v0 := NewValue("v0")
-	v1 := NewValue("v1")
-	e0 := NewValue("e0")
-	oe0 := ValueOut(v0, e0)
-	g0 := Null.AddValueIn(oe0, v1)
-	assert.Nil(t, Null.ValueVertex(v0))
-	assert.Nil(t, Null.ValueVertex(v1))
-	assert.NotNil(t, g0.ValueVertex(v0))
-	assert.NotNil(t, g0.ValueVertex(v1))
-
-	// half-edges should be re-usable
-	v2 := NewValue("v2")
-	v3a, v3b := NewValue("v3a"), NewValue("v3b")
-	e1 := NewValue("e1")
-	oe1 := ValueOut(v2, e1)
-	g1a := g0.AddValueIn(oe1, v3a)
-	g1b := g0.AddValueIn(oe1, v3b)
-	assertVertexEqual(t, value(v3a, edge(e1, value(v2))), g1a.ValueVertex(v3a))
-	assert.Nil(t, g1a.ValueVertex(v3b))
-	assertVertexEqual(t, value(v3b, edge(e1, value(v2))), g1b.ValueVertex(v3b))
-	assert.Nil(t, g1b.ValueVertex(v3a))
-
-	// ... even re-usable twice in succession
-	v3 := NewValue("v3")
-	v4 := NewValue("v4")
-	g2 := g0.AddValueIn(oe1, v3).AddValueIn(oe1, v4)
-	assert.Nil(t, g2.ValueVertex(v3b))
-	assert.Nil(t, g2.ValueVertex(v3a))
-	assertVertexEqual(t, value(v3, edge(e1, value(v2))), g2.ValueVertex(v3))
-	assertVertexEqual(t, value(v4, edge(e1, value(v2))), g2.ValueVertex(v4))
-}
-
-func TestGraphDelValueIn(t *T) {
-	v0 := NewValue("v0")
-	v1 := NewValue("v1")
-	e0 := NewValue("e0")
-	{ // removing from null
-		g := Null.DelValueIn(ValueOut(v0, e0), v1)
-		assert.True(t, Equal(Null, g))
-	}
-
-	e1 := NewValue("e1")
-	{ // removing edge from vertex which doesn't have that edge
-		g0 := Null.AddValueIn(ValueOut(v0, e0), v1)
-		g1 := g0.DelValueIn(ValueOut(v0, e1), v1)
-		assert.True(t, Equal(g0, g1))
-	}
-
-	{ // removing only edge
-		oe := ValueOut(v0, e0)
-		g0 := Null.AddValueIn(oe, v1)
-		g1 := g0.DelValueIn(oe, v1)
-		assert.True(t, Equal(Null, g1))
-	}
-
-	ej0 := NewValue("ej0")
-	v2 := NewValue("v2")
-	{ // removing only edge (junction)
-		oe := JunctionOut([]OpenEdge{
-			ValueOut(v0, e0),
-			ValueOut(v1, e1),
-		}, ej0)
-		g0 := Null.AddValueIn(oe, v2)
-		g1 := g0.DelValueIn(oe, v2)
-		assert.True(t, Equal(Null, g1))
-	}
-
-	{ // removing one of two edges
-		oe := ValueOut(v1, e0)
-		g0 := Null.AddValueIn(ValueOut(v0, e0), v2)
-		g1 := g0.AddValueIn(oe, v2)
-		g2 := g1.DelValueIn(oe, v2)
-		assert.True(t, Equal(g0, g2))
-		assert.NotNil(t, g2.ValueVertex(v0))
-		assert.Nil(t, g2.ValueVertex(v1))
-		assert.NotNil(t, g2.ValueVertex(v2))
-	}
-
-	e2 := NewValue("e2")
-	eja, ejb := NewValue("eja"), NewValue("ejb")
-	v3 := NewValue("v3")
-	{ // removing one of two edges (junction)
-		e0 := ValueOut(v0, e0)
-		e1 := ValueOut(v1, e1)
-		e2 := ValueOut(v2, e2)
-		oeA := JunctionOut([]OpenEdge{e0, e1}, eja)
-		oeB := JunctionOut([]OpenEdge{e1, e2}, ejb)
-		g0a := Null.AddValueIn(oeA, v3)
-		g0b := Null.AddValueIn(oeB, v3)
-		g1 := g0a.Union(g0b).DelValueIn(oeA, v3)
-		assert.True(t, Equal(g1, g0b))
-		assert.Nil(t, g1.ValueVertex(v0))
-		assert.NotNil(t, g1.ValueVertex(v1))
-		assert.NotNil(t, g1.ValueVertex(v2))
-		assert.NotNil(t, g1.ValueVertex(v3))
-	}
-
-	{ // removing one of two edges in circular graph
-		e0 := ValueOut(v0, e0)
-		e1 := ValueOut(v1, e1)
-		g0 := Null.AddValueIn(e0, v1).AddValueIn(e1, v0)
-		g1 := g0.DelValueIn(e0, v1)
-		assert.True(t, Equal(Null.AddValueIn(e1, v0), g1))
-		assert.NotNil(t, g1.ValueVertex(v0))
-		assert.NotNil(t, g1.ValueVertex(v1))
-	}
-
-	ej := NewValue("ej")
-	{ // removing to's only edge, sub-nodes have edge to each other
-		oej := JunctionOut([]OpenEdge{
-			ValueOut(v0, ej0),
-			ValueOut(v1, ej0),
-		}, ej)
-		g0 := Null.AddValueIn(oej, v2)
-		e0 := ValueOut(v0, e0)
-		g1 := g0.AddValueIn(e0, v1)
-		g2 := g1.DelValueIn(oej, v2)
-		assert.True(t, Equal(Null.AddValueIn(e0, v1), g2))
-		assert.NotNil(t, g2.ValueVertex(v0))
-		assert.NotNil(t, g2.ValueVertex(v1))
-		assert.Nil(t, g2.ValueVertex(v2))
-	}
-}
-
-// deterministically hashes a Graph
-func graphStr(g *Graph) string {
-	var vStr func(vertex) string
-	var oeStr func(OpenEdge) string
-	vStr = func(v vertex) string {
-		if v.VertexType == ValueVertex {
-			return fmt.Sprintf("v:%q\n", v.val.V.(string))
-		}
-		s := fmt.Sprintf("j:%d\n", len(v.in))
-		ssOE := make([]string, len(v.in))
-		for i := range v.in {
-			ssOE[i] = oeStr(v.in[i])
-		}
-		sort.Strings(ssOE)
-		return s + strings.Join(ssOE, "")
-	}
-	oeStr = func(oe OpenEdge) string {
-		s := fmt.Sprintf("oe:%q\n", oe.val.V.(string))
-		return s + vStr(oe.fromV)
-	}
-	sVV := make([]string, 0, len(g.vM))
-	for _, v := range g.vM {
-		sVV = append(sVV, vStr(v))
-	}
-	sort.Strings(sVV)
-	return strings.Join(sVV, "")
-}
-
-func assertEqualSets(t *T, exp, got []*Graph) bool {
-	if !assert.Equal(t, len(exp), len(got)) {
-		return false
-	}
-
-	m := map[*Graph]string{}
-	for _, g := range exp {
-		m[g] = graphStr(g)
-	}
-	for _, g := range got {
-		m[g] = graphStr(g)
-	}
-
-	sort.Slice(exp, func(i, j int) bool {
-		return m[exp[i]] < m[exp[j]]
-	})
-	sort.Slice(got, func(i, j int) bool {
-		return m[got[i]] < m[got[j]]
-	})
-
-	b := true
-	for i := range exp {
-		b = b || assert.True(t, Equal(exp[i], got[i]), "i:%d exp:%q got:%q", i, m[exp[i]], m[got[i]])
-	}
-	return b
-}
-
-func TestGraphUnion(t *T) {
-	assertUnion := func(g1, g2 *Graph) *Graph {
-		ga := g1.Union(g2)
-		gb := g2.Union(g1)
-		assert.True(t, Equal(ga, gb))
-		return ga
-	}
-
-	assertDisjoin := func(g *Graph, exp ...*Graph) {
-		ggDisj := g.Disjoin()
-		assertEqualSets(t, exp, ggDisj)
-	}
-
-	v0 := NewValue("v0")
-	v1 := NewValue("v1")
-	e0 := NewValue("e0")
-	{ // Union with Null
-		assert.True(t, Equal(Null, Null.Union(Null)))
-
-		g := Null.AddValueIn(ValueOut(v0, e0), v1)
-		assert.True(t, Equal(g, assertUnion(g, Null)))
-
-		assertDisjoin(g, g)
-	}
-
-	v2 := NewValue("v2")
-	v3 := NewValue("v3")
-	e1 := NewValue("e1")
-	{ // Two disparate graphs union'd
-		g0 := Null.AddValueIn(ValueOut(v0, e0), v1)
-		g1 := Null.AddValueIn(ValueOut(v2, e1), v3)
-		g := assertUnion(g0, g1)
-		assertVertexEqual(t, value(v0), g.ValueVertex(v0))
-		assertVertexEqual(t, value(v1, edge(e0, value(v0))), g.ValueVertex(v1))
-		assertVertexEqual(t, value(v2), g.ValueVertex(v2))
-		assertVertexEqual(t, value(v3, edge(e1, value(v2))), g.ValueVertex(v3))
-
-		assertDisjoin(g, g0, g1)
-	}
-
-	va0, vb0 := NewValue("va0"), NewValue("vb0")
-	va1, vb1 := NewValue("va1"), NewValue("vb1")
-	va2, vb2 := NewValue("va2"), NewValue("vb2")
-	ea0, eb0 := NewValue("ea0"), NewValue("eb0")
-	ea1, eb1 := NewValue("ea1"), NewValue("eb1")
-	eaj, ebj := NewValue("eaj"), NewValue("ebj")
-	{ // Two disparate graphs with junctions
-		ga := Null.AddValueIn(JunctionOut([]OpenEdge{
-			ValueOut(va0, ea0),
-			ValueOut(va1, ea1),
-		}, eaj), va2)
-		gb := Null.AddValueIn(JunctionOut([]OpenEdge{
-			ValueOut(vb0, eb0),
-			ValueOut(vb1, eb1),
-		}, ebj), vb2)
-		g := assertUnion(ga, gb)
-		assertVertexEqual(t, value(va0), g.ValueVertex(va0))
-		assertVertexEqual(t, value(va1), g.ValueVertex(va1))
-		assertVertexEqual(t,
-			value(va2, junction(eaj,
-				edge(ea0, value(va0)),
-				edge(ea1, value(va1)))),
-			g.ValueVertex(va2),
-		)
-		assertVertexEqual(t, value(vb0), g.ValueVertex(vb0))
-		assertVertexEqual(t, value(vb1), g.ValueVertex(vb1))
-		assertVertexEqual(t,
-			value(vb2, junction(ebj,
-				edge(eb0, value(vb0)),
-				edge(eb1, value(vb1)))),
-			g.ValueVertex(vb2),
-		)
-
-		assertDisjoin(g, ga, gb)
-	}
-
-	{ // Two partially overlapping graphs
-		g0 := Null.AddValueIn(ValueOut(v0, e0), v2)
-		g1 := Null.AddValueIn(ValueOut(v1, e1), v2)
-		g := assertUnion(g0, g1)
-		assertVertexEqual(t, value(v0), g.ValueVertex(v0))
-		assertVertexEqual(t, value(v1), g.ValueVertex(v1))
-		assertVertexEqual(t,
-			value(v2,
-				edge(e0, value(v0)),
-				edge(e1, value(v1)),
-			),
-			g.ValueVertex(v2),
-		)
-
-		assertDisjoin(g, g)
-	}
-
-	ej0 := NewValue("ej0")
-	ej1 := NewValue("ej1")
-	{ // two partially overlapping graphs with junctions
-		g0 := Null.AddValueIn(JunctionOut([]OpenEdge{
-			ValueOut(v0, e0),
-			ValueOut(v1, e1),
-		}, ej0), v2)
-		g1 := Null.AddValueIn(JunctionOut([]OpenEdge{
-			ValueOut(v0, e0),
-			ValueOut(v1, e1),
-		}, ej1), v2)
-		g := assertUnion(g0, g1)
-		assertVertexEqual(t, value(v0), g.ValueVertex(v0))
-		assertVertexEqual(t, value(v1), g.ValueVertex(v1))
-		assertVertexEqual(t,
-			value(v2,
-				junction(ej0, edge(e0, value(v0)), edge(e1, value(v1))),
-				junction(ej1, edge(e0, value(v0)), edge(e1, value(v1))),
-			),
-			g.ValueVertex(v2),
-		)
-
-		assertDisjoin(g, g)
-	}
-
-	{ // Two equal graphs
-		g0 := Null.AddValueIn(ValueOut(v0, e0), v1)
-		g := assertUnion(g0, g0)
-		assertVertexEqual(t, value(v0), g.ValueVertex(v0))
-		assertVertexEqual(t,
-			value(v1, edge(e0, value(v0))),
-			g.ValueVertex(v1),
-		)
-	}
-
-	{ // Two equal graphs with junctions
-		g0 := Null.AddValueIn(JunctionOut([]OpenEdge{
-			ValueOut(v0, e0),
-			ValueOut(v1, e1),
-		}, ej0), v2)
-		g := assertUnion(g0, g0)
-		assertVertexEqual(t, value(v0), g.ValueVertex(v0))
-		assertVertexEqual(t, value(v1), g.ValueVertex(v1))
-		assertVertexEqual(t,
-			value(v2,
-				junction(ej0, edge(e0, value(v0)), edge(e1, value(v1))),
-			),
-			g.ValueVertex(v2),
-		)
-	}
-}
-
-func TestGraphEqual(t *T) {
-	assertEqual := func(g1, g2 *Graph) {
-		assert.True(t, Equal(g1, g2))
-		assert.True(t, Equal(g2, g1))
-	}
-
-	assertNotEqual := func(g1, g2 *Graph) {
-		assert.False(t, Equal(g1, g2))
-		assert.False(t, Equal(g2, g1))
-	}
-
-	assertEqual(Null, Null) // duh
-
-	v0 := NewValue("v0")
-	v1 := NewValue("v1")
-	v2 := NewValue("v2")
-	e0 := NewValue("e0")
-	e1 := NewValue("e1")
-	e1a, e1b := NewValue("e1a"), NewValue("e1b")
-	{
-		// graph is equal to itself, not to null
-		e0 := ValueOut(v0, e0)
-		g0 := Null.AddValueIn(e0, v1)
-		assertNotEqual(g0, Null)
-		assertEqual(g0, g0)
-
-		// adding the an existing edge again shouldn't do anything
-		assertEqual(g0, g0.AddValueIn(e0, v1))
-
-		// g1a and g1b have the same vertices, but the edges are different
-		g1a := g0.AddValueIn(ValueOut(v0, e1a), v2)
-		g1b := g0.AddValueIn(ValueOut(v0, e1b), v2)
-		assertNotEqual(g1a, g1b)
-	}
-
-	{ // equal construction should yield equality, even if out of order
-		ga := Null.AddValueIn(ValueOut(v0, e0), v1)
-		ga = ga.AddValueIn(ValueOut(v1, e1), v2)
-		gb := Null.AddValueIn(ValueOut(v1, e1), v2)
-		gb = gb.AddValueIn(ValueOut(v0, e0), v1)
-		assertEqual(ga, gb)
-	}
-
-	ej := NewValue("ej")
-	{ // junction basic test
-		e0 := ValueOut(v0, e0)
-		e1 := ValueOut(v1, e1)
-		ga := Null.AddValueIn(JunctionOut([]OpenEdge{e0, e1}, ej), v2)
-		gb := Null.AddValueIn(JunctionOut([]OpenEdge{e1, e0}, ej), v2)
-		assertEqual(ga, ga)
-		assertNotEqual(ga, gb)
-	}
-}

gg/grammar/example_test.go

@@ -0,0 +1,154 @@
+package grammar_test
+
+import (
+	"bytes"
+	"fmt"
+	"strconv"
+	"strings"
+
+	"code.betamike.com/mediocregopher/ginger/gg/grammar"
+	"golang.org/x/exp/slices"
+)
+
+/*
+This example demonstrates how to describe the following EBNF using the grammar
+package:
+
+```
+<digit>           ::= "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"
+<positive-number> ::= <digit>+
+<negative-number> ::= "-" <positive-number>
+<number>          ::= <negative-number> | <positive-number>
+
+<list-el-tail> ::= <element> <list-tail>
+<list-tail>    ::= ")" | "," <list-el-tail>
+<list-head>    ::= ")" | <list-el-tail>
+<list>         ::= "(" <list-head>
+
+<element> ::= <number> | <list>
+```
+*/
+
+// Element represents an element of a list, which can be either a number or a
+// sub-list.
+type Element struct {
+	Number int64
+	List   []Element
+}
+
+func (e Element) String() string {
+	if e.List != nil {
+		listElStrs := make([]string, len(e.List))
+		for i := range e.List {
+			listElStrs[i] = e.List[i].String()
+		}
+		return fmt.Sprintf("(%s)", strings.Join(listElStrs, ","))
+	}
+
+	return fmt.Sprint(e.Number)
+}
+
+var (
+	digit = grammar.RuneFunc(
+		"digit", func(r rune) bool { return '0' <= r && r <= '9' },
+	)
+
+	positiveNumber = grammar.StringFromRunes(grammar.OneOrMore(digit))
+
+	negativeNumber = grammar.Reduction(
+		grammar.Rune('-'),
+		positiveNumber,
+		func(
+			neg grammar.Located[rune], posNum grammar.Located[string],
+		) grammar.Located[string] {
+			return grammar.Locate(neg.Location, string(neg.Value)+posNum.Value)
+		},
+	)
+
+	number = grammar.Named(
+		"number",
+		grammar.Mapping(
+			grammar.FirstOf(negativeNumber, positiveNumber),
+			func(str grammar.Located[string]) Element {
+				i, err := strconv.ParseInt(str.Value, 10, 64)
+				if err != nil {
+					panic(fmt.Errorf("parsing %q as int: %w", str, err))
+				}
+				return Element{Number: i}
+			},
+		),
+	)
+
+	// Because the list/element definitions are recursive it requires using
+	// SymbolPtrs, which is easier to do via a global initialization function
+	// like this.
+	list = func() grammar.Symbol[Element] {
+
+		type listState []Element
+
+		var (
+			listTail = new(grammar.SymbolPtr[listState])
+			list     = new(grammar.SymbolPtr[Element])
+			element  = new(grammar.SymbolPtr[Element])
+
+			// Right parenthesis indicates the end of a list, at which point we
+			// can initialize the state which gets returned down the stack.
+			listTerm = grammar.Mapping(
+				grammar.Rune(')'),
+				func(grammar.Located[rune]) listState { return listState{} },
+			)
+
+			listElTail = grammar.Reduction[Element, listState, listState](
+				element,
+				listTail,
+				func(el Element, ls listState) listState {
+					ls = append(ls, el)
+					return ls
+				},
+			)
+
+			listHead = grammar.FirstOf(listTerm, listElTail)
+		)
+
+		listTail.Symbol = grammar.FirstOf(
+			listTerm,
+			grammar.Prefixed(grammar.Rune(','), listElTail),
+		)
+
+		list.Symbol = grammar.Named(
+			"list",
+			grammar.Reduction[grammar.Located[rune], listState, Element](
+				grammar.Rune('('),
+				listHead,
+				func(_ grammar.Located[rune], ls listState) Element {
+					slices.Reverse(ls)
+					return Element{List: []Element(ls)}
+				},
+			),
+		)
+
+		element.Symbol = grammar.FirstOf[Element](number, list)
+
+		return list
+	}()
+)
+
+func Example() {
+	r := grammar.NewReader(bytes.NewBufferString(
+		`()` + `(1,(2,-3),4)` + `(ERROR`,
+	))
+
+	l1, err := list.Decode(r)
+	fmt.Println(l1, err)
+
+	l2, err := list.Decode(r)
+	fmt.Println(l2, err)
+
+	_, err = list.Decode(r)
+	fmt.Println(err)
+
+	// Output:
+	// () <nil>
+	// (1,(2,-3),4) <nil>
+	// 1:16: expected ')' or number or list
+}

gg/grammar/grammar.go

@@ -0,0 +1,27 @@
+// Package grammar is used for parsing a stream of runes according to a set of
+// grammatical rules. This package only supports context-free grammars.
+package grammar
+
+import "fmt"
+
+// Stringer is a convenience tool for working with fmt.Stringer. Exactly one of
+// the fields must be set, and will be used to implement the fmt.Stringer
+// interface.
+type Stringer struct {
+	I fmt.Stringer
+	F func() string
+	S string
+}
+
+func (s Stringer) String() string {
+	switch {
+	case s.I != nil:
+		return s.I.String()
+	case s.F != nil:
+		return s.F()
+	case s.S != "":
+		return s.S
+	default:
+		panic("no fields set on Stringer")
+	}
+}

gg/grammar/location.go

@@ -0,0 +1,32 @@
+package grammar
+
+import "fmt"
+
+// Location indicates a position in a stream of runes identified by column
+// within newline-separated rows.
+type Location struct {
+	Row, Col int
+}
+
+func (l Location) errf(str string, args ...any) LocatedError {
+	return LocatedError{l, fmt.Errorf(str, args...)}
+}
+
+// Located wraps a value so that it has a Location attached to it.
+type Located[T any] struct {
+	Location
+	Value T
+}
+
+// Locate returns a Located instance combining the given values.
+func Locate[T any](l Location, v T) Located[T] {
+	return Located[T]{l, v}
+}
+
+// LocatedError is an error related to a specific point within a stream of
+// runes.
+type LocatedError Located[error]
+
+func (e LocatedError) Error() string {
+	return fmt.Sprintf("%d:%d: %v", e.Row, e.Col, e.Value)
+}

gg/grammar/reader.go

@@ -0,0 +1,74 @@
+package grammar
+
+import (
+	"bufio"
+	"io"
+)
+
+// Reader is used for reading Runes from a stream.
+type Reader interface {
+
+	// ReadRune reads the next Rune off the stream, or returns io.EOF.
+	ReadRune() (Located[rune], error)
+
+	// UnreadRune can be used to place a Rune onto an internal buffer, such that
+	// the Rune will be the next to be read using ReadRune. If called multiple
+	// times then ReadRune will produce the given Runes in LIFO order.
+	UnreadRune(Located[rune])
+
+	// NextLocation returns the Location of the next Rune which will be returned
+	// with ReadRune.
+	NextLocation() Location
+}
+
+type reader struct {
+	br        *bufio.Reader
+	brNextLoc Location
+
+	unread []Located[rune]
+}
+
+// NewReader wraps the io.Reader as a Reader. The given Reader should not be
+// read from after this call.
+func NewReader(r io.Reader) Reader {
+	return &reader{
+		br:        bufio.NewReader(r),
+		brNextLoc: Location{Row: 1, Col: 1},
+	}
+}
+
+func (rr *reader) ReadRune() (Located[rune], error) {
+	if len(rr.unread) > 0 {
+		r := rr.unread[len(rr.unread)-1]
+		rr.unread = rr.unread[:len(rr.unread)-1]
+		return r, nil
+	}
+
+	loc := rr.brNextLoc
+
+	r, _, err := rr.br.ReadRune()
+	if err != nil {
+		return Located[rune]{}, err
+	}
+
+	if r == '\n' {
+		rr.brNextLoc.Row++
+		rr.brNextLoc.Col = 1
+	} else {
+		rr.brNextLoc.Col++
+	}
+
+	return Located[rune]{loc, r}, nil
+}
+
+func (rr *reader) UnreadRune(r Located[rune]) {
+	rr.unread = append(rr.unread, r)
+}
+
+func (rr *reader) NextLocation() Location {
+	if len(rr.unread) > 0 {
+		return rr.unread[len(rr.unread)-1].Location
+	}
+
+	return rr.brNextLoc
+}

gg/grammar/symbol.go

@@ -0,0 +1,306 @@
+package grammar
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+)
+
+// ErrNoMatch is used by Symbol's Decode method, see that method's docs for more
+// details.
+var ErrNoMatch = errors.New("no match")
+
+// Symbol represents a symbol in the grammar. A Symbol is expected to be
+// stateless, and is usually constructed from other Symbols using functions in
+// this package.
+type Symbol[T any] interface {
+	fmt.Stringer // Used when generating errors related to this Symbol, e.g. "number"
+
+	// Decode reads and parses a value represented by this Symbol off the
+	// Reader.
+	//
+	// This may return ErrNoMatch to indicate that the upcoming data on the
+	// Reader is rejected by this Symbol. In this case the Symbol should leave
+	// the Reader in the same state it was passed.
+	Decode(Reader) (T, error)
+}
+
+type symbol[T any] struct {
+	fmt.Stringer
+	decodeFn func(Reader) (T, error)
+}
+
+func (s *symbol[T]) Decode(r Reader) (T, error) { return s.decodeFn(r) }
+
+// SymbolPtr wraps a Symbol in a such a way as to make lazily initializing a
+// Symbol variable possible. This allows for recursion amongst different
+// Symbols.
+//
+// Example:
+//
+//	a := new(SymbolPtr)
+//	b := new(SymbolPtr)
+//	a.Symbol = FirstOf(Rune('a'), b)
+//	b.Symbol = FirstOf(Rune('b'), a)
+type SymbolPtr[T any] struct {
+	Symbol[T]
+}
+
+func named[T any](stringer fmt.Stringer, sym Symbol[T]) Symbol[T] {
+	return &symbol[T]{
+		stringer,
+		sym.Decode,
+	}
+}
+
+// Named wraps the given Symbol such that its String method returns the given
+// name.
+func Named[T any](name string, sym Symbol[T]) Symbol[T] {
+	return named(Stringer{S: name}, sym)
+}
+
+// RuneFunc matches and produces any rune for which the given function returns
+// true.
+func RuneFunc(name string, fn func(rune) bool) Symbol[Located[rune]] {
+	return &symbol[Located[rune]]{
+		Stringer{S: name},
+		func(rr Reader) (Located[rune], error) {
+			var zero Located[rune]
+
+			r, err := rr.ReadRune()
+			if errors.Is(err, io.EOF) {
+				return zero, ErrNoMatch
+			} else if err != nil {
+				return zero, err
+			}
+
+			if !fn(r.Value) {
+				rr.UnreadRune(r)
+				return zero, ErrNoMatch
+			}
+
+			return r, nil
+		},
+	}
+}
+
+// Rune matches and produces the given rune.
+func Rune(r rune) Symbol[Located[rune]] {
+	return RuneFunc(
+		fmt.Sprintf("'%c'", r),
+		func(r2 rune) bool { return r == r2 },
+	)
+}
+
+// StringFromRunes produces a string from the slice of runes produced by the
+// given Symbol. The slice must not be empty. StringFromRunes does not match if
+// the given Symbol does not match.
+func StringFromRunes(sym Symbol[[]Located[rune]]) Symbol[Located[string]] {
+	return Mapping(sym, func(runes []Located[rune]) Located[string] {
+		if len(runes) == 0 {
+			panic("StringFromRunes used on empty set of runes")
+		}
+
+		str := make([]rune, len(runes))
+		for i := range runes {
+			str[i] = runes[i].Value
+		}
+		return Located[string]{runes[0].Location, string(str)}
+	})
+}
+
+// Mapping produces a value of type Tb by decoding a value from the given
+// Symbol and passing it through the given mapping function. If the given Symbol
+// doesn't match then neither does Map.
+func Mapping[Ta, Tb any](
+	sym Symbol[Ta], fn func(Ta) Tb,
+) Symbol[Tb] {
+	return &symbol[Tb]{
+		sym,
+		func(rr Reader) (Tb, error) {
+			var zero Tb
+			va, err := sym.Decode(rr)
+			if err != nil {
+				return zero, err
+			}
+			return fn(va), nil
+		},
+	}
+}
+
+// OneOrMore will produce as many of the given Symbol's value as can be found
+// sequentially, up until a non-matching value is encountered. If no matches are
+// found then OneOrMore does not match.
+func OneOrMore[T any](sym Symbol[T]) Symbol[[]T] {
+	return &symbol[[]T]{
+		Stringer{F: func() string {
+			return fmt.Sprintf("one or more %v", sym)
+		}},
+		func(rr Reader) ([]T, error) {
+			var vv []T
+			for {
+				v, err := sym.Decode(rr)
+				if errors.Is(err, ErrNoMatch) {
+					break
+				} else if err != nil {
+					return nil, err
+				}
+
+				vv = append(vv, v)
+			}
+
+			if len(vv) == 0 {
+				return nil, ErrNoMatch
+			}
+
+			return vv, nil
+		},
+	}
+}
+
+// ZeroOrMore will produce as many of the given Symbol's value as can be found
+// sequentially, up until a non-matching value is encountered. If no matches are
+// found then an empty slice is produced.
+func ZeroOrMore[T any](sym Symbol[T]) Symbol[[]T] {
+	return &symbol[[]T]{
+		Stringer{F: func() string {
+			return fmt.Sprintf("zero or more %v", sym)
+		}},
+		func(rr Reader) ([]T, error) {
+			var vv []T
+			for {
+				v, err := sym.Decode(rr)
+				if errors.Is(err, ErrNoMatch) {
+					break
+				} else if err != nil {
+					return nil, err
+				}
+
+				vv = append(vv, v)
+			}
+
+			return vv, nil
+		},
+	}
+}
+
+func firstOf[T any](stringer fmt.Stringer, syms ...Symbol[T]) Symbol[T] {
+	return &symbol[T]{
+		stringer,
+		func(rr Reader) (T, error) {
+			var zero T
+			for _, sym := range syms {
+				v, err := sym.Decode(rr)
+				if errors.Is(err, ErrNoMatch) {
+					continue
+				} else if err != nil {
+					return zero, err
+				}
+
+				return v, nil
+			}
+
+			return zero, ErrNoMatch
+		},
+	}
+}
+
+// FirstOf matches and produces the value for the first Symbol in the list which
+// matches. FirstOf does not match if none of the given Symbols match.
+func FirstOf[T any](syms ...Symbol[T]) Symbol[T] {
+	return firstOf(
+		Stringer{F: func() string {
+			descrs := make([]string, len(syms))
+			for i := range syms {
+				descrs[i] = syms[i].String()
+			}
+			return strings.Join(descrs, " or ")
+		}},
+		syms...,
+	)
+}
+
+// Reduction produces a value of type Tc by first reading a value from symA,
+// then symB, and then running those through the given function.
+//
+// If symA does not match then Reduction does not match. If symA matches but
+// symB does not then also match then Reduction produces a LocatedError.
+func Reduction[Ta, Tb, Tc any](
+	symA Symbol[Ta],
+	symB Symbol[Tb],
+	fn func(Ta, Tb) Tc,
+) Symbol[Tc] {
+	return &symbol[Tc]{
+		symA,
+		func(rr Reader) (Tc, error) {
+			var zero Tc
+
+			va, err := symA.Decode(rr)
+			if err != nil {
+				return zero, err
+			}
+
+			vb, err := symB.Decode(rr)
+			if errors.Is(err, ErrNoMatch) {
+				return zero, rr.NextLocation().errf("expected %v", symB)
+			} else if err != nil {
+				return zero, err
+			}
+
+			return fn(va, vb), nil
+
+		},
+	}
+}
+
+// Prefixed matches on prefixSym, discards its value, then produces the value
+// produced by sym.
+//
+// If prefixSym does not match then Prefixed does not match. If prefixSym
+// matches but sym does not also match then Prefixed produces a LocatedError.
+func Prefixed[Ta, Tb any](prefixSym Symbol[Ta], sym Symbol[Tb]) Symbol[Tb] {
+	return named(prefixSym, Reduction(prefixSym, sym, func(_ Ta, b Tb) Tb {
+		return b
+	}))
+}
+
+// PrefixDiscarded is similar to Prefixed, except that if sym does not match
+// then PrefixDiscarded does not match, whereas Prefixed produces a LocatedError
+// in that case.
+//
+// NOTE PrefixDiscarded does not fully honor the contract of Symbol. If
+// prefixSym matches, but sym does not, then only sym will restore Reader to its
+// prior state; prefixSym cannot return whatever data it read back onto the
+// Reader. Therefore ErrNoMatch can be returned without Reader being fully back
+// in its original state. In practice this isn't a big deal, given the common
+// use-cases of PrefixDiscarded, but it may prove tricky.
+func PrefixDiscarded[Ta, Tb any](prefixSym Symbol[Ta], sym Symbol[Tb]) Symbol[Tb] {
+	return &symbol[Tb]{
+		sym,
+		func(rr Reader) (Tb, error) {
+			var zero Tb
+			if _, err := prefixSym.Decode(rr); err != nil {
+				return zero, err
+			}
+			return sym.Decode(rr)
+		},
+	}
+}
+
+// Suffixed matchs on sym and then suffixSym, returning the value produced by
+// sym and discarding the one produced by suffixSym.
+//
+// If sym does not match then Suffixed does not match. If sym matches but
+// suffixSym does not also match then Suffixed produces a LocatedError.
+func Suffixed[Ta, Tb any](sym Symbol[Ta], suffixSym Symbol[Tb]) Symbol[Ta] {
+	return named(sym, Reduction(sym, suffixSym, func(a Ta, _ Tb) Ta {
+		return a
+	}))
+}
+
+// Discard matches if the given Symbol does, but discards the value it produces,
+// producing an empty value instead.
+func Discard[T any](sym Symbol[T]) Symbol[struct{}] {
+	return Mapping(sym, func(T) struct{} { return struct{}{} })
+}

gg/json.go

@@ -1,186 +0,0 @@
-package gg
-
-import (
-	"encoding/json"
-	"fmt"
-)
-
-type openEdgeJSON struct {
-	From    vertexJSON `json:"from"`
-	ValueID string     `json:"valueID"`
-}
-
-type vertexJSON struct {
-	Type    VertexType     `json:"type"`
-	ValueID string         `json:"valueID,omitempty"`
-	In      []openEdgeJSON `json:"in"`
-}
-
-type graphJSON struct {
-	Values        map[string]json.RawMessage `json:"values"`
-	ValueVertices []vertexJSON               `json:"valueVertices"`
-}
-
-// MarshalJSON implements the json.Marshaler interface for a Graph. All Values
-// in the Graph will have json.Marshal called on them as-is in order to marshal
-// them.
-func (g *Graph) MarshalJSON() ([]byte, error) {
-	gJ := graphJSON{
-		Values:        map[string]json.RawMessage{},
-		ValueVertices: make([]vertexJSON, 0, len(g.vM)),
-	}
-
-	withVal := func(val Value) (string, error) {
-		if _, ok := gJ.Values[val.ID]; !ok {
-			valJ, err := json.Marshal(val.V)
-			if err != nil {
-				return "", err
-			}
-			gJ.Values[val.ID] = json.RawMessage(valJ)
-		}
-		return val.ID, nil
-	}
-
-	// two locally defined, mutually recursive functions. This kind of thing
-	// could probably be abstracted out, I feel like it happens frequently with
-	// graph code.
-	var mkIns func([]OpenEdge) ([]openEdgeJSON, error)
-	var mkVert func(vertex) (vertexJSON, error)
-
-	mkIns = func(in []OpenEdge) ([]openEdgeJSON, error) {
-		inJ := make([]openEdgeJSON, len(in))
-		for i := range in {
-			valID, err := withVal(in[i].val)
-			if err != nil {
-				return nil, err
-			}
-			vJ, err := mkVert(in[i].fromV)
-			if err != nil {
-				return nil, err
-			}
-			inJ[i] = openEdgeJSON{From: vJ, ValueID: valID}
-		}
-		return inJ, nil
-	}
-
-	mkVert = func(v vertex) (vertexJSON, error) {
-		ins, err := mkIns(v.in)
-		if err != nil {
-			return vertexJSON{}, err
-		}
-		vJ := vertexJSON{
-			Type: v.VertexType,
-			In:   ins,
-		}
-		if v.VertexType == ValueVertex {
-			valID, err := withVal(v.val)
-			if err != nil {
-				return vJ, err
-			}
-			vJ.ValueID = valID
-		}
-		return vJ, nil
-	}
-
-	for _, v := range g.vM {
-		vJ, err := mkVert(v)
-		if err != nil {
-			return nil, err
-		}
-		gJ.ValueVertices = append(gJ.ValueVertices, vJ)
-	}
-
-	return json.Marshal(gJ)
-}
-
-type jsonUnmarshaler struct {
-	g  *Graph
-	fn func(json.RawMessage) (interface{}, error)
-}
-
-// JSONUnmarshaler returns a json.Unmarshaler instance which, when used, will
-// unmarshal a json string into the Graph instance being called on here.
-//
-// The passed in function is used to unmarshal Values (used in both ValueVertex
-// vertices and edges) from json strings into go values. The returned inteface{}
-// should have already had the unmarshal from the given json string performed on
-// it.
-//
-// The json.Unmarshaler returned can be used many times, but will reset the
-// Graph completely before each use.
-func (g *Graph) JSONUnmarshaler(fn func(json.RawMessage) (interface{}, error)) json.Unmarshaler {
-	return jsonUnmarshaler{g: g, fn: fn}
-}
-
-func (jm jsonUnmarshaler) UnmarshalJSON(b []byte) error {
-	*(jm.g) = Graph{}
-	jm.g.vM = map[string]vertex{}
-
-	var gJ graphJSON
-	if err := json.Unmarshal(b, &gJ); err != nil {
-		return err
-	}
-
-	vals := map[string]Value{}
-	getVal := func(valID string) (Value, error) {
-		if val, ok := vals[valID]; ok {
-			return val, nil
-		}
-
-		j, ok := gJ.Values[valID]
-		if !ok {
-			return Value{}, fmt.Errorf("unmarshaling malformed graph, value with ID %q not defined", valID)
-		}
-
-		V, err := jm.fn(j)
-		if err != nil {
-			return Value{}, err
-		}
-
-		val := Value{ID: valID, V: V}
-		vals[valID] = val
-		return val, nil
-	}
-
-	var mkIns func([]openEdgeJSON) ([]OpenEdge, error)
-	var mkVert func(vertexJSON) (vertex, error)
-
-	mkIns = func(inJ []openEdgeJSON) ([]OpenEdge, error) {
-		in := make([]OpenEdge, len(inJ))
-		for i := range inJ {
-			val, err := getVal(inJ[i].ValueID)
-			if err != nil {
-				return nil, err
-			}
-			v, err := mkVert(inJ[i].From)
-			if err != nil {
-				return nil, err
-			}
-			in[i] = OpenEdge{fromV: v, val: val}
-		}
-		return in, nil
-	}
-
-	mkVert = func(vJ vertexJSON) (vertex, error) {
-		ins, err := mkIns(vJ.In)
-		if err != nil {
-			return vertex{}, err
-		}
-		var val Value
-		if vJ.Type == ValueVertex {
-			if val, err = getVal(vJ.ValueID); err != nil {
-				return vertex{}, err
-			}
-		}
-		return mkVertex(vJ.Type, val, ins...), nil
-	}
-
-	for _, v := range gJ.ValueVertices {
-		v, err := mkVert(v)
-		if err != nil {
-			return err
-		}
-		jm.g.vM[v.id] = v
-	}
-	return nil
-}

gim/NOTES

@@ -1,111 +0,0 @@
-Notes from reading https://www.graphviz.org/Documentation/TSE93.pdf, which
-describes an algorithm for drawing an acyclic graph in basically the way which I
-want.
-
-This document assumes the primary flow of drawing is downward, and secondary is
-right.
-
-For all of this it might be easier to not even consider edge values yet, as
-those could be done by converting them into vertices themselves after the
-cyclic-edge-reversal and then converting them back later.
-
-Drawing the graph is a four step process:
-
-1) Rank nodes in the Y axis
-    - Graph must be acyclic.
-        - This can be accomplished by strategically reversing edges which cause
-          a cycle, and then reversing them back as a post-processing step.
-        - Edges can be found by:
-            - walking out from a particular node depth-first from some arbitrary
-              node.
-            - As you do so you assign a rank based on depth to each node you
-              encounter.
-            - If any edge is destined for a node which has already been seen you
-              look at the ranks of the source and destination, and if the source
-              is _greater_ than the destination you reverse the edge's
-              direction.
-        - I think that algorithm only works if there's a source/sink? might have
-          to be modified, or the walk must traverse both to & from.
-    - Assign all edges a weight, default 1, but possibly externally assigned to
-      be greater.
-    - Take a "feasible" minimum spanning tree (MST) of the graph
-        - Feasibility is defined as each edge being "tight", meaning, once you
-          rank each node by their distance from the root and define the length
-          of an edge as the difference of rank of its head and tail, that each
-          tree edge will have a length of 1.
-    - Perform the following on the MST:
-        - For each edge of the graph assign the cut value
-            - If you were to remove any edge of an MST it would create two
-              separate MSTs. The side the edge was pointing from is the tail,
-              the side it was pointing to is the head.
-            - Looking at edges _in the original graph_, sum the weights of all
-              edges directed from the tail to the head (including the one
-              removed) and subtract from that the sum of the weights of the
-              edges directed from the head to the tail. This is the cut value.
-            - "...note that the cut values can be computed using information
-              local to an edge if the search is ordered from the leaves of the
-              feasible tree inward. It is trivial to compute the cut value of a
-              tree edge with one of its endpoints a leaf in the tree, since
-              either the head or the tail component consists of a single node.
-              Now, assuming the cut values are known for all the edges incident
-              on a given node except one, the cut value of the remaining edge is
-              the sum of the known cut values plus a term dependent only on the
-              edges incident to the given node."
-        - Take an edge with a negative cut value and remove it. Find the graph
-          edge between the remaining head and tail MSTs with the smallest
-          "slack" (distance in rank between its ends) and add that edge to the
-          MST to make it connected again.
-        - Repeat until there are no negative cut values.
-        - Apparently searching "cyclically" through the negative edges, rather
-          than iterating from the start each time, is worthwhile.
-    - Normalize the MST by assigning the root node the rank of 0 (and so on), if
-      it changed.
-    - All edges in the MST are of length 1, and the rest can be inferred from
-      that.
-    - To reduce crowding, nodes with equal in/out edge weights and which could
-      be placed on multiple rankings are moved to the ranking with the fewest
-      nodes.
-
-2) Order nodes in the X axis to reduce edge crossings
-    - Add ephemeral vertices along edges with lengths greater than 1, so all
-      "spaces" are filled.
-    - If any vertices have edges to vertices on their same rank, those are
-      ordered so that all these "flag edges" are pointed in the same direction
-      across that rank, and the ordering of those particular vertices is always
-      kept.
-    - Iterate over the graph some fixed number of times (the paper recommends
-      24)
-        - possibly with some heuristic which looks at percentage improvement
-          each time to determine if it's worth the effort.
-        - on one iteration move "down" the graph, on the next move "up", etc...
-          shaker style
-        - On each iteration:
-            - For each vertex look at the median position of all of the vertices
-              it has edges to in the previous rank
-            - If the number of previous vertices is even do this complicated
-              thing (P is the set of positions previous):
-              ```
-              if |P| = 2 then
-                return (P[0] + P[1])/2;
-              else
-                left = P[m-1] - P[0];
-                right = P[|P| -1] - P[m];
-                return (P[m-1]*right + P[m]*left)/(left+right);
-              endif
-              ```
-            - Sort the vertices by their median position
-                - vertices with no previous vertices remain fixed
-            - Then, for each vertex in the rank attempt to transpose it with its
-              neighbor and see if that reduces the number of edge crossings
-              between the rank and its previous.
-            - If equality is found during these two steps (same median, or same
-              number of crossings) the vertices in question should be flipped.
-
-3) Compute node coordinates
-    - Determining the Y coordinates is considered trivial: find the maxHeight of
-      each rank, and ensure they are separated by that much plus whatever the
-      separation value is.
-    - For the X coordinates: do some insane shit involving the network simplex
-      again.
-
-4) Determine edge splines

gim/geo/geo.go

@@ -1,139 +0,0 @@
-// Package geo implements basic geometric concepts used by gim
-package geo
-
-import "math"
-
-// XY describes a 2-dimensional position or vector. The origin of the
-// 2-dimensional space is a 0,0, with the x-axis going to the left and the
-// y-axis going down.
-type XY [2]int
-
-// Zero is the zero point, or a zero vector, depending on what you're doing
-var Zero = XY{0, 0}
-
-// Unit vectors
-var (
-	Up    = XY{0, -1}
-	Down  = XY{0, 1}
-	Left  = XY{-1, 0}
-	Right = XY{1, 0}
-)
-
-// Units is the set of unit vectors
-var Units = []XY{
-	Up,
-	Down,
-	Left,
-	Right,
-}
-
-func (xy XY) toF64() [2]float64 {
-	return [2]float64{
-		float64(xy[0]),
-		float64(xy[1]),
-	}
-}
-
-func abs(i int) int {
-	if i < 0 {
-		return i * -1
-	}
-	return i
-}
-
-// Abs returns the XY with all fields made positive, if they weren't already
-func (xy XY) Abs() XY {
-	return XY{abs(xy[0]), abs(xy[1])}
-}
-
-// Unit returns the XY with each field divided by its absolute value (i.e.
-// scaled down to 1 or -1). Fields which are 0 are left alone
-func (xy XY) Unit() XY {
-	for i := range xy {
-		if xy[i] > 0 {
-			xy[i] = 1
-		} else if xy[i] < 0 {
-			xy[i] = -1
-		}
-	}
-	return xy
-}
-
-// Len returns the length (aka magnitude) of the XY as a vector.
-func (xy XY) Len() int {
-	if xy[0] == 0 {
-		return abs(xy[1])
-	} else if xy[1] == 0 {
-		return abs(xy[0])
-	}
-
-	xyf := xy.toF64()
-	lf := math.Sqrt((xyf[0] * xyf[0]) + (xyf[1] * xyf[1]))
-	return Rounder.Round(lf)
-}
-
-// Add returns the result of adding the two XYs' fields individually
-func (xy XY) Add(xy2 XY) XY {
-	xy[0] += xy2[0]
-	xy[1] += xy2[1]
-	return xy
-}
-
-// Mul returns the result of multiplying the two XYs' fields individually
-func (xy XY) Mul(xy2 XY) XY {
-	xy[0] *= xy2[0]
-	xy[1] *= xy2[1]
-	return xy
-}
-
-// Div returns the results of dividing the two XYs' field individually.
-func (xy XY) Div(xy2 XY) XY {
-	xyf, xy2f := xy.toF64(), xy2.toF64()
-	return XY{
-		Rounder.Round(xyf[0] / xy2f[0]),
-		Rounder.Round(xyf[1] / xy2f[1]),
-	}
-}
-
-// Scale returns the result of multiplying both of the XY's fields by the scalar
-func (xy XY) Scale(scalar int) XY {
-	return xy.Mul(XY{scalar, scalar})
-}
-
-// Inv inverses the XY, a shortcut for xy.Scale(-1)
-func (xy XY) Inv() XY {
-	return xy.Scale(-1)
-}
-
-// Sub subtracts xy2 from xy and returns the result. A shortcut for
-// xy.Add(xy2.Inv())
-func (xy XY) Sub(xy2 XY) XY {
-	return xy.Add(xy2.Inv())
-}
-
-// Midpoint returns the midpoint between the two XYs.
-func (xy XY) Midpoint(xy2 XY) XY {
-	return xy.Add(xy2.Sub(xy).Div(XY{2, 2}))
-}
-
-// Min returns an XY whose fields are the minimum values of the two XYs'
-// fields compared individually
-func (xy XY) Min(xy2 XY) XY {
-	for i := range xy {
-		if xy2[i] < xy[i] {
-			xy[i] = xy2[i]
-		}
-	}
-	return xy
-}
-
-// Max returns an XY whose fields are the Maximum values of the two XYs'
-// fields compared individually
-func (xy XY) Max(xy2 XY) XY {
-	for i := range xy {
-		if xy2[i] > xy[i] {
-			xy[i] = xy2[i]
-		}
-	}
-	return xy
-}

gim/geo/rect.go

@@ -1,127 +0,0 @@
-package geo
-
-import (
-	"fmt"
-)
-
-// Rect describes a rectangle based on the position of its top-left corner and
-// size
-type Rect struct {
-	TopLeft XY
-	Size    XY
-}
-
-// Edge describes a straight edge starting at its first XY and ending at its
-// second
-type Edge [2]XY
-
-// EdgeCoord returns the coordinate of the edge indicated by the given direction
-// (Up, Down, Left, or Right). The coordinate will be for the axis applicable to
-// the direction, so for Left/Right it will be the x coordinate and for Up/Down
-// the y.
-func (r Rect) EdgeCoord(dir XY) int {
-	switch dir {
-	case Up:
-		return r.TopLeft[1]
-	case Down:
-		return r.TopLeft[1] + r.Size[1] - 1
-	case Left:
-		return r.TopLeft[0]
-	case Right:
-		return r.TopLeft[0] + r.Size[0] - 1
-	default:
-		panic(fmt.Sprintf("unsupported direction: %#v", dir))
-	}
-}
-
-// Corner returns the position of the corner identified by the given directions
-// (Left/Right, Up/Down)
-func (r Rect) Corner(xDir, yDir XY) XY {
-	switch {
-	case r.Size[0] == 0 || r.Size[1] == 0:
-		panic(fmt.Sprintf("rectangle with non-multidimensional size has no corners: %v", r.Size))
-	case xDir == Left && yDir == Up:
-		return r.TopLeft
-	case xDir == Right && yDir == Up:
-		return r.TopLeft.Add(r.Size.Mul(Right)).Add(XY{-1, 0})
-	case xDir == Left && yDir == Down:
-		return r.TopLeft.Add(r.Size.Mul(Down)).Add(XY{0, -1})
-	case xDir == Right && yDir == Down:
-		return r.TopLeft.Add(r.Size).Add(XY{-1, -1})
-	default:
-		panic(fmt.Sprintf("unsupported Corner args: %v, %v", xDir, yDir))
-	}
-}
-
-// Edge returns an Edge instance for the edge of the Rect indicated by the given
-// direction (Up, Down, Left, or Right). secDir indicates the direction the
-// returned Edge should be pointing (i.e. the order of its XY's) and must be
-// perpendicular to dir
-func (r Rect) Edge(dir, secDir XY) Edge {
-	var e Edge
-	switch dir {
-	case Up:
-		e[0], e[1] = r.Corner(Left, Up), r.Corner(Right, Up)
-	case Down:
-		e[0], e[1] = r.Corner(Left, Down), r.Corner(Right, Down)
-	case Left:
-		e[0], e[1] = r.Corner(Left, Up), r.Corner(Left, Down)
-	case Right:
-		e[0], e[1] = r.Corner(Right, Up), r.Corner(Right, Down)
-	default:
-		panic(fmt.Sprintf("unsupported direction: %#v", dir))
-	}
-
-	switch secDir {
-	case Left, Up:
-		e[0], e[1] = e[1], e[0]
-	default:
-		// do nothing
-	}
-	return e
-}
-
-// Midpoint returns the point which is the midpoint of the Edge
-func (e Edge) Midpoint() XY {
-	return e[0].Midpoint(e[1])
-}
-
-func (r Rect) halfSize() XY {
-	return r.Size.Div(XY{2, 2})
-}
-
-// Center returns the centerpoint of the rectangle.
-func (r Rect) Center() XY {
-	return r.TopLeft.Add(r.halfSize())
-}
-
-// Translate returns an instance of Rect which is the same as this one but
-// translated by the given amount.
-func (r Rect) Translate(by XY) Rect {
-	r.TopLeft = r.TopLeft.Add(by)
-	return r
-}
-
-// Centered returns an instance of Rect which is this one but translated to be
-// centered on the given point.
-func (r Rect) Centered(on XY) Rect {
-	r.TopLeft = on.Sub(r.halfSize())
-	return r
-}
-
-// Union returns the smallest Rect which encompasses the given Rect and the one
-// being called upon.
-func (r Rect) Union(r2 Rect) Rect {
-	if r.Size == Zero {
-		return r2
-	} else if r2.Size == Zero {
-		return r
-	}
-
-	tl := r.TopLeft.Min(r2.TopLeft)
-	br := r.Corner(Right, Down).Max(r2.Corner(Right, Down))
-	return Rect{
-		TopLeft: tl,
-		Size:    br.Sub(tl).Add(XY{1, 1}),
-	}
-}

gim/geo/rect_test.go

@@ -1,113 +0,0 @@
-package geo
-
-import (
-	. "testing"
-
-	"github.com/stretchr/testify/assert"
-)
-
-func TestRect(t *T) {
-	r := Rect{
-		TopLeft: XY{1, 2},
-		Size:    XY{2, 2},
-	}
-
-	assert.Equal(t, 2, r.EdgeCoord(Up))
-	assert.Equal(t, 3, r.EdgeCoord(Down))
-	assert.Equal(t, 1, r.EdgeCoord(Left))
-	assert.Equal(t, 2, r.EdgeCoord(Right))
-
-	lu := XY{1, 2}
-	ld := XY{1, 3}
-	ru := XY{2, 2}
-	rd := XY{2, 3}
-
-	assert.Equal(t, lu, r.Corner(Left, Up))
-	assert.Equal(t, ld, r.Corner(Left, Down))
-	assert.Equal(t, ru, r.Corner(Right, Up))
-	assert.Equal(t, rd, r.Corner(Right, Down))
-
-	assert.Equal(t, Edge{lu, ld}, r.Edge(Left, Down))
-	assert.Equal(t, Edge{ru, rd}, r.Edge(Right, Down))
-	assert.Equal(t, Edge{lu, ru}, r.Edge(Up, Right))
-	assert.Equal(t, Edge{ld, rd}, r.Edge(Down, Right))
-	assert.Equal(t, Edge{ld, lu}, r.Edge(Left, Up))
-	assert.Equal(t, Edge{rd, ru}, r.Edge(Right, Up))
-	assert.Equal(t, Edge{ru, lu}, r.Edge(Up, Left))
-	assert.Equal(t, Edge{rd, ld}, r.Edge(Down, Left))
-}
-
-func TestRectCenter(t *T) {
-	assertCentered := func(exp, given Rect, center XY) {
-		got := given.Centered(center)
-		assert.Equal(t, exp, got)
-		assert.Equal(t, center, got.Center())
-	}
-
-	{
-		r := Rect{
-			Size: XY{4, 4},
-		}
-		assert.Equal(t, XY{2, 2}, r.Center())
-		assertCentered(
-			Rect{TopLeft: XY{1, 1}, Size: XY{4, 4}},
-			r, XY{3, 3},
-		)
-	}
-
-	{
-		r := Rect{
-			Size: XY{5, 5},
-		}
-		assert.Equal(t, XY{3, 3}, r.Center())
-		assertCentered(
-			Rect{TopLeft: XY{0, 0}, Size: XY{5, 5}},
-			r, XY{3, 3},
-		)
-	}
-}
-
-func TestRectUnion(t *T) {
-	assertUnion := func(exp, r1, r2 Rect) {
-		assert.Equal(t, exp, r1.Union(r2))
-		assert.Equal(t, exp, r2.Union(r1))
-	}
-
-	{ // Zero
-		r := Rect{TopLeft: XY{1, 1}, Size: XY{2, 2}}
-		assertUnion(r, r, Rect{})
-	}
-
-	{ // Equal
-		r := Rect{Size: XY{2, 2}}
-		assertUnion(r, r, r)
-	}
-
-	{ // Overlapping corner
-		r1 := Rect{TopLeft: XY{0, 0}, Size: XY{2, 2}}
-		r2 := Rect{TopLeft: XY{1, 1}, Size: XY{2, 2}}
-		ex := Rect{TopLeft: XY{0, 0}, Size: XY{3, 3}}
-		assertUnion(ex, r1, r2)
-	}
-
-	{ // 2 overlapping corners
-		r1 := Rect{TopLeft: XY{0, 0}, Size: XY{4, 4}}
-		r2 := Rect{TopLeft: XY{1, 1}, Size: XY{4, 2}}
-		ex := Rect{TopLeft: XY{0, 0}, Size: XY{5, 4}}
-		assertUnion(ex, r1, r2)
-	}
-
-	{ // Shared edge
-		r1 := Rect{TopLeft: XY{0, 0}, Size: XY{2, 1}}
-		r2 := Rect{TopLeft: XY{1, 0}, Size: XY{1, 2}}
-		ex := Rect{TopLeft: XY{0, 0}, Size: XY{2, 2}}
-		assertUnion(ex, r1, r2)
-	}
-
-	{ // Adjacent edge
-		r1 := Rect{TopLeft: XY{0, 0}, Size: XY{2, 2}}
-		r2 := Rect{TopLeft: XY{2, 0}, Size: XY{2, 2}}
-		ex := Rect{TopLeft: XY{0, 0}, Size: XY{4, 2}}
-		assertUnion(ex, r1, r2)
-	}
-}

gim/geo/round.go

@@ -1,33 +0,0 @@
-package geo
-
-import (
-	"math"
-)
-
-// RounderFunc is a function which converts a floating point number into an
-// integer.
-type RounderFunc func(float64) int64
-
-// Round is helper for calling the RounderFunc and converting the result to an
-// int.
-func (rf RounderFunc) Round(f float64) int {
-	return int(rf(f))
-}
-
-// A few RounderFuncs which can be used. Set the Rounder global variable to pick
-// one.
-var (
-	Floor RounderFunc = func(f float64) int64 { return int64(math.Floor(f)) }
-	Ceil  RounderFunc = func(f float64) int64 { return int64(math.Ceil(f)) }
-	Round RounderFunc = func(f float64) int64 {
-		if f < 0 {
-			f = math.Ceil(f - 0.5)
-		}
-		f = math.Floor(f + 0.5)
-		return int64(f)
-	}
-)
-
-// Rounder is the RounderFunc which will be used by all functions and methods in
-// this package when needed.
-var Rounder = Ceil

gim/main.go

@@ -1,91 +0,0 @@
-package main
-
-import (
-	"math/rand"
-	"time"
-
-	"github.com/mediocregopher/ginger/gg"
-	"github.com/mediocregopher/ginger/gim/geo"
-	"github.com/mediocregopher/ginger/gim/terminal"
-	"github.com/mediocregopher/ginger/gim/view"
-)
-
-// TODO be able to draw circular graphs
-// TODO audit all steps, make sure everything is deterministic
-// TODO self-edges
-
-//const (
-//	framerate   = 10
-//	frameperiod = time.Second / time.Duration(framerate)
-//)
-
-//func debugf(str string, args ...interface{}) {
-//	if !strings.HasSuffix(str, "\n") {
-//		str += "\n"
-//	}
-//	fmt.Fprintf(os.Stderr, str, args...)
-//}
-
-func mkGraph() (*gg.Graph, gg.Value) {
-	a := gg.NewValue("a")
-	aE0 := gg.NewValue("aE0")
-	aE1 := gg.NewValue("aE1")
-	aE2 := gg.NewValue("aE2")
-	aE3 := gg.NewValue("aE3")
-	b0 := gg.NewValue("b0")
-	b1 := gg.NewValue("b1")
-	b2 := gg.NewValue("b2")
-	b3 := gg.NewValue("b3")
-	oaE0 := gg.ValueOut(a, aE0)
-	oaE1 := gg.ValueOut(a, aE1)
-	oaE2 := gg.ValueOut(a, aE2)
-	oaE3 := gg.ValueOut(a, aE3)
-	g := gg.Null
-	g = g.AddValueIn(oaE0, b0)
-	g = g.AddValueIn(oaE1, b1)
-	g = g.AddValueIn(oaE2, b2)
-	g = g.AddValueIn(oaE3, b3)
-
-	c := gg.NewValue("c")
-	empty := gg.NewValue("")
-	jE := gg.JunctionOut([]gg.OpenEdge{
-		gg.ValueOut(b0, empty),
-		gg.ValueOut(b1, empty),
-		gg.ValueOut(b2, empty),
-		gg.ValueOut(b3, empty),
-	}, gg.NewValue("jE"))
-	g = g.AddValueIn(jE, c)
-
-	// TODO this really fucks it up
-	//d := gg.NewValue("d")
-	//deE := gg.ValueOut(d, gg.NewValue("deE"))
-	//g = g.AddValueIn(deE, gg.NewValue("e"))
-
-	return g, c
-}
-
-//func mkGraph() *gg.Graph {
-//	g := gg.Null
-//	g = g.AddValueIn(gg.ValueOut(str("a"), str("e")), str("b"))
-//	return g
-//}
-
-func main() {
-	rand.Seed(time.Now().UnixNano())
-	term := terminal.New()
-	wSize := term.WindowSize()
-	center := geo.Zero.Midpoint(wSize)
-
-	g, start := mkGraph()
-	view := view.New(g, start, geo.Right, geo.Down)
-	viewBuf := terminal.NewBuffer()
-	view.Draw(viewBuf)
-
-	buf := terminal.NewBuffer()
-	buf.DrawBufferCentered(center, viewBuf)
-
-	term.Clear()
-	term.WriteBuffer(geo.Zero, buf)
-	term.SetPos(wSize.Add(geo.XY{0, -1}))
-	term.Draw()
-}

gim/terminal/buffer.go

@@ -1,217 +0,0 @@
-package terminal
-
-import (
-	"fmt"
-	"strconv"
-	"unicode"
-
-	"github.com/mediocregopher/ginger/gim/geo"
-)
-
-// Reset all custom styles
-const ansiReset = "\033[0m"
-
-// Color describes the foreground or background color of text
-type Color int
-
-// Available Color values
-const (
-	// whatever the terminal's default color scheme is
-	Default = iota
-
-	Black
-	Red
-	Green
-	Yellow
-	Blue
-	Magenta
-	Cyan
-	White
-)
-
-type bufStyle struct {
-	fgColor Color
-	bgColor Color
-}
-
-// returns foreground and background ansi codes
-func (bf bufStyle) ansi() (string, string) {
-	var fg, bg string
-	if bf.fgColor != Default {
-		fg = "\033[0;3" + strconv.Itoa(int(bf.fgColor)-1) + "m"
-	}
-	if bf.bgColor != Default {
-		bg = "\033[0;4" + strconv.Itoa(int(bf.bgColor)-1) + "m"
-	}
-	return fg, bg
-}
-
-// returns the ansi sequence which would modify the style to the given one
-func (bf bufStyle) diffTo(bf2 bufStyle) string {
-	// this implementation is naive, but whatever
-	if bf == bf2 {
-		return ""
-	}
-
-	fg, bg := bf2.ansi()
-	if (bf == bufStyle{}) {
-		return fg + bg
-	}
-	return ansiReset + fg + bg
-}
-
-type bufPoint struct {
-	r rune
-	bufStyle
-}
-
-// Buffer describes an infinitely sized terminal buffer to which anything may be
-// drawn, and which will efficiently generate strings representing the drawn
-// text.
-type Buffer struct {
-	currStyle bufStyle
-	currPos   geo.XY
-	m         *mat
-	max       geo.XY
-}
-
-// NewBuffer initializes and returns a new empty buffer. The proper way to clear
-// a buffer is to toss the old one and generate a new one.
-func NewBuffer() *Buffer {
-	return &Buffer{
-		m:   newMat(),
-		max: geo.XY{-1, -1},
-	}
-}
-
-// Copy creates a new identical instance of this Buffer and returns it.
-func (b *Buffer) Copy() *Buffer {
-	b2 := NewBuffer()
-	b.m.iter(func(x, y int, v interface{}) bool {
-		b2.setRune(geo.XY{x, y}, v.(bufPoint))
-		return true
-	})
-	b2.currStyle = b.currStyle
-	b2.currPos = b.currPos
-	return b2
-}
-
-func (b *Buffer) setRune(at geo.XY, p bufPoint) {
-	b.m.set(at[0], at[1], p)
-	b.max = b.max.Max(at)
-}
-
-// WriteRune writes the given rune to the Buffer at whatever the current
-// position is, with whatever the current styling is.
-func (b *Buffer) WriteRune(r rune) {
-	if r == '\n' {
-		b.currPos[0], b.currPos[1] = 0, b.currPos[1]+1
-		return
-	} else if r == '\r' {
-		b.currPos[0] = 0
-	} else if !unicode.IsPrint(r) {
-		panic(fmt.Sprintf("character %q is not supported by terminal.Buffer", r))
-	}
-
-	b.setRune(b.currPos, bufPoint{
-		r:        r,
-		bufStyle: b.currStyle,
-	})
-	b.currPos[0]++
-}
-
-// WriteString writes the given string to the Buffer at whatever the current
-// position is, with whatever the current styling is.
-func (b *Buffer) WriteString(s string) {
-	for _, r := range s {
-		b.WriteRune(r)
-	}
-}
-
-// SetPos sets the cursor position in the Buffer, so Print operations will begin
-// at that point. Remember that the origin is at point (0, 0).
-func (b *Buffer) SetPos(xy geo.XY) {
-	b.currPos = xy
-}
-
-// SetFGColor sets subsequent text's foreground color.
-func (b *Buffer) SetFGColor(c Color) {
-	b.currStyle.fgColor = c
-}
-
-// SetBGColor sets subsequent text's background color.
-func (b *Buffer) SetBGColor(c Color) {
-	b.currStyle.bgColor = c
-}
-
-// ResetStyle unsets all text styling options which have been set.
-func (b *Buffer) ResetStyle() {
-	b.currStyle = bufStyle{}
-}
-
-// String renders and returns a string which, when printed to a terminal, will
-// print the Buffer's contents at the terminal's current cursor position.
-func (b *Buffer) String() string {
-	s := ansiReset // always start with a reset
-	var style bufStyle
-	var pos geo.XY
-	move := func(to geo.XY) {
-		diff := to.Sub(pos)
-		if diff[0] > 0 {
-			s += "\033[" + strconv.Itoa(diff[0]) + "C"
-		} else if diff[0] < 0 {
-			s += "\033[" + strconv.Itoa(-diff[0]) + "D"
-		}
-		if diff[1] > 0 {
-			s += "\033[" + strconv.Itoa(diff[1]) + "B"
-		} else if diff[1] < 0 {
-			s += "\033[" + strconv.Itoa(-diff[1]) + "A"
-		}
-		pos = to
-	}
-
-	b.m.iter(func(x, y int, v interface{}) bool {
-		p := v.(bufPoint)
-		move(geo.XY{x, y})
-		s += style.diffTo(p.bufStyle)
-		style = p.bufStyle
-		s += string(p.r)
-		pos[0]++
-		return true
-	})
-	return s
-}
-
-// DrawBuffer copies the given Buffer onto this one, with the given's top-left
-// corner being at the given position. The given buffer may be the same as this
-// one.
-//
-// Calling this method does not affect this Buffer's current cursor position or
-// style.
-func (b *Buffer) DrawBuffer(at geo.XY, b2 *Buffer) {
-	if b == b2 {
-		b2 = b2.Copy()
-	}
-	b2.m.iter(func(x, y int, v interface{}) bool {
-		x += at[0]
-		y += at[1]
-		if x < 0 || y < 0 {
-			return true
-		}
-		b.setRune(geo.XY{x, y}, v.(bufPoint))
-		return true
-	})
-}
-
-// DrawBufferCentered is like DrawBuffer, but centered around the given point
-// instead of translated by it.
-func (b *Buffer) DrawBufferCentered(around geo.XY, b2 *Buffer) {
-	b2rect := geo.Rect{Size: b2.Size()}
-	b.DrawBuffer(b2rect.Centered(around).TopLeft, b2)
-}
-
-// Size returns the dimensions of the Buffer's current area which has been
-// written to.
-func (b *Buffer) Size() geo.XY {
-	return b.max.Add(geo.XY{1, 1})
-}

gim/terminal/example/main.go

@@ -1,59 +0,0 @@
-package main
-
-import (
-	"log"
-	"time"
-
-	"github.com/mediocregopher/ginger/gim/geo"
-	"github.com/mediocregopher/ginger/gim/terminal"
-)
-
-func main() {
-	b := terminal.NewBuffer()
-	b.WriteString("this is fun")
-
-	b.SetFGColor(terminal.Blue)
-	b.SetBGColor(terminal.Green)
-	b.SetPos(geo.XY{18, 0})
-	b.WriteString("blue and green")
-
-	b.ResetStyle()
-	b.SetFGColor(terminal.Red)
-	b.SetPos(geo.XY{3, 3})
-	b.WriteString("red!!!")
-
-	b.ResetStyle()
-	b.SetFGColor(terminal.Blue)
-	b.SetPos(geo.XY{20, 0})
-	b.WriteString("boo")
-
-	bcp := b.Copy()
-	b.DrawBuffer(geo.XY{2, 2}, bcp)
-	b.DrawBuffer(geo.XY{-1, 1}, bcp)
-
-	brect := terminal.NewBuffer()
-	brect.DrawRect(geo.Rect{Size: b.Size().Add(geo.XY{2, 2})}, terminal.SingleLine)
-	log.Printf("b.Size:%v", b.Size())
-	brect.DrawBuffer(geo.XY{1, 1}, b)
-
-	t := terminal.New()
-	p := geo.XY{0, 0}
-	dirH, dirV := geo.Right, geo.Down
-	wsize := t.WindowSize()
-	for range time.Tick(time.Second / 15) {
-		t.Clear()
-		t.WriteBuffer(p, brect)
-		t.Draw()
-
-		brectSize := brect.Size()
-		p = p.Add(dirH).Add(dirV)
-		if p[0] < 0 || p[0]+brectSize[0] > wsize[0] {
-			dirH = dirH.Scale(-1)
-			p = p.Add(dirH.Scale(2))
-		}
-		if p[1] < 0 || p[1]+brectSize[1] > wsize[1] {
-			dirV = dirV.Scale(-1)
-			p = p.Add(dirV.Scale(2))
-		}
-	}
-}

gim/terminal/mat.go

@@ -1,117 +0,0 @@
-package terminal
-
-import (
-	"container/list"
-)
-
-type matEl struct {
-	x int
-	v interface{}
-}
-
-type matRow struct {
-	y int
-	l *list.List
-}
-
-// a 2-d sparse matrix
-type mat struct {
-	rows *list.List
-
-	currY     int
-	currRowEl *list.Element
-	currEl    *list.Element
-}
-
-func newMat() *mat {
-	return &mat{
-		rows: list.New(),
-	}
-}
-
-func (m *mat) getRow(y int) *list.List {
-	m.currY = y             // this will end up being true no matter what
-	if m.currRowEl == nil { // first call
-		l := list.New()
-		m.currRowEl = m.rows.PushFront(matRow{y: y, l: l})
-		return l
-
-	} else if m.currRowEl.Value.(matRow).y > y {
-		m.currRowEl = m.rows.Front()
-	}
-
-	for {
-		currRow := m.currRowEl.Value.(matRow)
-		switch {
-		case currRow.y == y:
-			return currRow.l
-		case currRow.y < y:
-			if m.currRowEl = m.currRowEl.Next(); m.currRowEl == nil {
-				l := list.New()
-				m.currRowEl = m.rows.PushBack(matRow{y: y, l: l})
-				return l
-			}
-		default: // currRow.y > y
-			l := list.New()
-			m.currRowEl = m.rows.InsertBefore(matRow{y: y, l: l}, m.currRowEl)
-			return l
-		}
-	}
-}
-
-func (m *mat) getEl(x, y int) *matEl {
-	var rowL *list.List
-	if m.currRowEl == nil || m.currY != y {
-		rowL = m.getRow(y)
-		m.currEl = rowL.Front()
-	} else {
-		rowL = m.currRowEl.Value.(matRow).l
-	}
-
-	if m.currEl == nil || m.currEl.Value.(*matEl).x > x {
-		if m.currEl = rowL.Front(); m.currEl == nil {
-			// row is empty
-			mel := &matEl{x: x}
-			m.currEl = rowL.PushFront(mel)
-			return mel
-		}
-	}
-
-	for {
-		currEl := m.currEl.Value.(*matEl)
-		switch {
-		case currEl.x == x:
-			return currEl
-		case currEl.x < x:
-			if m.currEl = m.currEl.Next(); m.currEl == nil {
-				mel := &matEl{x: x}
-				m.currEl = rowL.PushBack(mel)
-				return mel
-			}
-		default: // currEl.x > x
-			mel := &matEl{x: x}
-			m.currEl = rowL.InsertBefore(mel, m.currEl)
-			return mel
-		}
-	}
-}
-
-func (m *mat) get(x, y int) interface{} {
-	return m.getEl(x, y).v
-}
-
-func (m *mat) set(x, y int, v interface{}) {
-	m.getEl(x, y).v = v
-}
-
-func (m *mat) iter(f func(x, y int, v interface{}) bool) {
-	for rowEl := m.rows.Front(); rowEl != nil; rowEl = rowEl.Next() {
-		row := rowEl.Value.(matRow)
-		for el := row.l.Front(); el != nil; el = el.Next() {
-			mel := el.Value.(*matEl)
-			if !f(mel.x, row.y, mel.v) {
-				return
-			}
-		}
-	}
-}

gim/terminal/mat_test.go

@@ -1,59 +0,0 @@
-package terminal
-
-import (
-	"fmt"
-	"math/rand"
-	"strings"
-	. "testing"
-	"time"
-)
-
-func TestMat(t *T) {
-	r := rand.New(rand.NewSource(time.Now().UnixNano()))
-
-	type xy struct {
-		x, y int
-	}
-
-	type action struct {
-		xy
-		set int
-	}
-
-	run := func(aa []action) {
-		aaStr := func(i int) string {
-			s := fmt.Sprintf("%#v", aa[:i+1])
-			return strings.Replace(s, "terminal.", "", -1)
-		}
-
-		m := newMat()
-		mm := map[xy]int{}
-		for i, a := range aa {
-			if a.set > 0 {
-				mm[a.xy] = a.set
-				m.set(a.xy.x, a.xy.y, a.set)
-				continue
-			}
-
-			expI, expOk := mm[a.xy]
-			gotI, gotOk := m.get(a.xy.x, a.xy.y).(int)
-			if expOk != gotOk {
-				t.Fatalf("get failed: expOk:%v gotOk:%v actions:%#v", expOk, gotOk, aaStr(i))
-			} else if expI != gotI {
-				t.Fatalf("get failed: expI:%v gotI:%v actions:%#v", expI, gotI, aaStr(i))
-			}
-		}
-	}
-
-	for i := 0; i < 10000; i++ {
-		var actions []action
-		for j := r.Intn(1000); j > 0; j-- {
-			a := action{xy: xy{x: r.Intn(5), y: r.Intn(5)}}
-			if r.Intn(3) == 0 {
-				a.set = r.Intn(10000) + 1
-			}
-			actions = append(actions, a)
-		}
-		run(actions)
-	}
-}

gim/terminal/shape.go

@@ -1,189 +0,0 @@
-package terminal
-
-import (
-	"fmt"
-	"strings"
-
-	"github.com/mediocregopher/ginger/gim/geo"
-)
-
-// SingleLine is a set of single-pixel-width lines.
-var SingleLine = LineStyle{
-	Horiz:       '─',
-	Vert:        '│',
-	TopLeft:     '┌',
-	TopRight:    '┐',
-	BottomLeft:  '└',
-	BottomRight: '┘',
-	PerpUp:      '┴',
-	PerpDown:    '┬',
-	PerpLeft:    '┤',
-	PerpRight:   '├',
-	ArrowUp:     '^',
-	ArrowDown:   'v',
-	ArrowLeft:   '<',
-	ArrowRight:  '>',
-}
-
-// LineStyle defines a set of characters to use together when drawing lines and
-// corners.
-type LineStyle struct {
-	Horiz, Vert rune
-
-	// Corner characters, identified as corners of a rectangle
-	TopLeft, TopRight, BottomLeft, BottomRight rune
-
-	// Characters for a straight segment a perpendicular attached
-	PerpUp, PerpDown, PerpLeft, PerpRight rune
-
-	// Characters for pointing arrows
-	ArrowUp, ArrowDown, ArrowLeft, ArrowRight rune
-}
-
-// Segment takes two different directions (i.e. geo.Up/Down/Left/Right) and
-// returns the line character which points in both of those directions.
-//
-// For example, SingleLine.Segment(geo.Up, geo.Left) returns '┘'.
-func (ls LineStyle) Segment(a, b geo.XY) rune {
-	inner := func(a, b geo.XY) rune {
-		type c struct{ a, b geo.XY }
-		switch (c{a, b}) {
-		case c{geo.Up, geo.Down}:
-			return ls.Vert
-		case c{geo.Left, geo.Right}:
-			return ls.Horiz
-		case c{geo.Down, geo.Right}:
-			return ls.TopLeft
-		case c{geo.Down, geo.Left}:
-			return ls.TopRight
-		case c{geo.Up, geo.Right}:
-			return ls.BottomLeft
-		case c{geo.Up, geo.Left}:
-			return ls.BottomRight
-		default:
-			return 0
-		}
-	}
-	if r := inner(a, b); r != 0 {
-		return r
-	} else if r = inner(b, a); r != 0 {
-		return r
-	}
-	panic(fmt.Sprintf("invalid LineStyle.Segment directions: %v, %v", a, b))
-}
-
-// Perpendicular returns the line character for a perpendicular segment
-// traveling in the given direction.
-func (ls LineStyle) Perpendicular(dir geo.XY) rune {
-	switch dir {
-	case geo.Up:
-		return ls.PerpUp
-	case geo.Down:
-		return ls.PerpDown
-	case geo.Left:
-		return ls.PerpLeft
-	case geo.Right:
-		return ls.PerpRight
-	default:
-		panic(fmt.Sprintf("invalid LineStyle.Perpendicular direction: %v", dir))
-	}
-}
-
-// Arrow returns the arrow character for an arrow pointing in the given
-// direction.
-func (ls LineStyle) Arrow(dir geo.XY) rune {
-	switch dir {
-	case geo.Up:
-		return ls.ArrowUp
-	case geo.Down:
-		return ls.ArrowDown
-	case geo.Left:
-		return ls.ArrowLeft
-	case geo.Right:
-		return ls.ArrowRight
-	default:
-		panic(fmt.Sprintf("invalid LineStyle.Arrow direction: %v", dir))
-	}
-}
-
-// DrawRect draws the given Rect to the Buffer with the given LineStyle. The
-// Rect's TopLeft field is used for its position.
-//
-// If Rect's Size is not at least 2x2 this does nothing.
-func (b *Buffer) DrawRect(r geo.Rect, ls LineStyle) {
-	if r.Size[0] < 2 || r.Size[1] < 2 {
-		return
-	}
-	horiz := strings.Repeat(string(ls.Horiz), r.Size[0]-2)
-
-	b.SetPos(r.TopLeft)
-	b.WriteRune(ls.TopLeft)
-	b.WriteString(horiz)
-	b.WriteRune(ls.TopRight)
-
-	for i := 0; i < r.Size[1]-2; i++ {
-		b.SetPos(r.TopLeft.Add(geo.XY{0, i + 1}))
-		b.WriteRune(ls.Vert)
-		b.SetPos(r.TopLeft.Add(geo.XY{r.Size[0] - 1, i + 1}))
-		b.WriteRune(ls.Vert)
-	}
-
-	b.SetPos(r.TopLeft.Add(geo.XY{0, r.Size[1] - 1}))
-	b.WriteRune(ls.BottomLeft)
-	b.WriteString(horiz)
-	b.WriteRune(ls.BottomRight)
-}
-
-// DrawLine draws a line from the start point to the ending one, primarily
-// moving in the given direction, using the given LineStyle to do so.
-func (b *Buffer) DrawLine(start, end, dir geo.XY, ls LineStyle) {
-	// given the "primary" direction the line should be headed, pick a possible
-	// secondary one which may be used to detour along the path in order to
-	// reach the destination (in the case that the two boxes are diagonal from
-	// each other)
-	var perpDir geo.XY
-	perpDir[0], perpDir[1] = dir[1], dir[0]
-	dirSec := end.Sub(start).Mul(perpDir.Abs()).Unit()
-	mid := start.Midpoint(end)
-
-	along := func(xy, dir geo.XY) int {
-		if dir[0] != 0 {
-			return xy[0]
-		}
-		return xy[1]
-	}
-
-	// collect the points along the line into an array
-	var pts []geo.XY
-	var curr geo.XY
-	midPrim := along(mid, dir)
-	endSec := along(end, dirSec)
-	for curr = start; curr != end; {
-		pts = append(pts, curr)
-		if prim := along(curr, dir); prim == midPrim {
-			if sec := along(curr, dirSec); sec != endSec {
-				curr = curr.Add(dirSec)
-				continue
-			}
-		}
-		curr = curr.Add(dir)
-	}
-	pts = append(pts, curr) // appending end
-
-	// draw each point
-	for i, pt := range pts {
-		var prev, next geo.XY
-		switch {
-		case i == 0:
-			prev = pt.Add(dir.Inv())
-			next = pts[i+1]
-		case i == len(pts)-1:
-			prev = pts[i-1]
-			next = pt.Add(dir)
-		default:
-			prev, next = pts[i-1], pts[i+1]
-		}
-		b.SetPos(pt)
-		b.WriteRune(ls.Segment(prev.Sub(pt), next.Sub(pt)))
-	}
-}

gim/terminal/terminal.go

@@ -1,108 +0,0 @@
-// Package terminal implements functionality related to interacting with a
-// terminal. Using this package takes the place of using stdout directly
-package terminal
-
-import (
-	"bytes"
-	"fmt"
-	"io"
-	"os"
-	"syscall"
-	"unsafe"
-
-	"github.com/mediocregopher/ginger/gim/geo"
-)
-
-// Terminal provides an interface to a terminal which allows for "drawing"
-// rather than just writing. Note that all operations on a Terminal aren't
-// actually drawn to the screen until Flush is called.
-//
-// The coordinate system described by Terminal looks like this:
-//
-// 0,0 ------------------> x
-//  |
-//  |
-//  |
-//  |
-//  |
-//  |
-//  |
-//  |
-//  v
-//  y
-//
-type Terminal struct {
-	buf *bytes.Buffer
-
-	// When initialized this will be set to os.Stdout, but can be set to
-	// anything
-	Out io.Writer
-}
-
-// New initializes and returns a usable Terminal
-func New() *Terminal {
-	return &Terminal{
-		buf: new(bytes.Buffer),
-		Out: os.Stdout,
-	}
-}
-
-// WindowSize returns the size of the terminal window (width/height)
-// TODO this doesn't support winblows
-func (t *Terminal) WindowSize() geo.XY {
-	var sz struct {
-		rows    uint16
-		cols    uint16
-		xpixels uint16
-		ypixels uint16
-	}
-	_, _, err := syscall.Syscall(
-		syscall.SYS_IOCTL,
-		uintptr(syscall.Stdin),
-		uintptr(syscall.TIOCGWINSZ),
-		uintptr(unsafe.Pointer(&sz)),
-	)
-	if err != 0 {
-		panic(err.Error())
-	}
-	return geo.XY{int(sz.cols), int(sz.rows)}
-}
-
-// SetPos sets the terminal's actual cursor position to the given coordinates.
-func (t *Terminal) SetPos(to geo.XY) {
-	// actual terminal uses 1,1 as top-left, because 1-indexing is a great idea
-	fmt.Fprintf(t.buf, "\033[%d;%dH", to[1]+1, to[0]+1)
-}
-
-// HideCursor causes the cursor to not actually be shown
-func (t *Terminal) HideCursor() {
-	fmt.Fprintf(t.buf, "\033[?25l")
-}
-
-// ShowCursor causes the cursor to be shown, if it was previously hidden
-func (t *Terminal) ShowCursor() {
-	fmt.Fprintf(t.buf, "\033[?25h")
-}
-
-// Clear completely clears all drawn characters on the screen and returns the
-// cursor to the origin. This implicitly calls Draw.
-func (t *Terminal) Clear() {
-	t.buf.Reset()
-	fmt.Fprintf(t.buf, "\033[2J")
-	t.Draw()
-}
-
-// WriteBuffer writes the contents to the Buffer to the Terminal's buffer,
-// starting at the given coordinate.
-func (t *Terminal) WriteBuffer(at geo.XY, b *Buffer) {
-	t.SetPos(at)
-	t.buf.WriteString(b.String())
-}
-
-// Draw writes all buffered changes to the screen
-func (t *Terminal) Draw() {
-	if _, err := io.Copy(t.Out, t.buf); err != nil {
-		panic(err)
-	}
-	t.buf.Reset()
-}

gim/view/box.go

@@ -1,66 +0,0 @@
-package view
-
-import (
-	"fmt"
-
-	"github.com/mediocregopher/ginger/gg"
-	"github.com/mediocregopher/ginger/gim/geo"
-	"github.com/mediocregopher/ginger/gim/terminal"
-)
-
-type box struct {
-	topLeft       geo.XY
-	flowDir       geo.XY
-	numIn, numOut int
-	buf           *terminal.Buffer
-	bodyBuf       *terminal.Buffer
-}
-
-func boxFromVertex(v *gg.Vertex, flowDir geo.XY) box {
-	b := box{
-		flowDir: flowDir,
-		numIn:   len(v.In),
-		numOut:  len(v.Out),
-	}
-	if v.VertexType == gg.ValueVertex {
-		b.bodyBuf = terminal.NewBuffer()
-		b.bodyBuf.WriteString(v.Value.V.(string))
-	}
-	return b
-}
-
-func (b box) rect() geo.Rect {
-	var bodyRect geo.Rect
-	if b.bodyBuf != nil {
-		bodyRect.Size = b.bodyBuf.Size().Add(geo.XY{2, 2})
-	}
-
-	var edgesRect geo.Rect
-	{
-		var neededByEdges int
-		if b.numIn > b.numOut {
-			neededByEdges = b.numIn*2 + 1
-		} else {
-			neededByEdges = b.numOut*2 + 1
-		}
-
-		switch b.flowDir {
-		case geo.Left, geo.Right:
-			edgesRect.Size = geo.XY{2, neededByEdges}
-		case geo.Up, geo.Down:
-			edgesRect.Size = geo.XY{neededByEdges, 2}
-		default:
-			panic(fmt.Sprintf("unknown flowDir: %#v", b.flowDir))
-		}
-	}
-
-	return bodyRect.Union(edgesRect).Translate(b.topLeft)
-}
-
-func (b box) draw(buf *terminal.Buffer) {
-	rect := b.rect()
-	buf.DrawRect(rect, terminal.SingleLine)
-	if b.bodyBuf != nil {
-		buf.DrawBufferCentered(rect.Center(), b.bodyBuf)
-	}
-}

gim/view/constraint/constraint.go

@@ -1,119 +0,0 @@
-// Package constraint implements an extremely simple constraint engine.
-// Elements, and constraints on those elements, are given to the engine, which
-// uses those constraints to generate an output. Elements are defined as a
-// string
-package constraint
-
-import (
-	"github.com/mediocregopher/ginger/gg"
-)
-
-// Constraint describes a constraint on an element. The Elem field must be
-// filled in, as well as exactly one other field
-type Constraint struct {
-	Elem string
-
-	// LT says that Elem is less than this element
-	LT string
-}
-
-var ltEdge = gg.NewValue("lt")
-
-// Engine processes sets of constraints to generate an output
-type Engine struct {
-	g    *gg.Graph
-	vals map[string]gg.Value
-}
-
-// NewEngine initializes and returns an empty Engine
-func NewEngine() *Engine {
-	return &Engine{g: gg.Null, vals: map[string]gg.Value{}}
-}
-
-func (e *Engine) getVal(elem string) gg.Value {
-	if val, ok := e.vals[elem]; ok {
-		return val
-	}
-	val := gg.NewValue(elem)
-	e.vals[elem] = val
-	return val
-}
-
-// AddConstraint adds the given constraint to the engine's set, returns false if
-// the constraint couldn't be added due to a conflict with a previous constraint
-func (e *Engine) AddConstraint(c Constraint) bool {
-	elem := e.getVal(c.Elem)
-	g := e.g.AddValueIn(gg.ValueOut(elem, ltEdge), e.getVal(c.LT))
-
-	// Check for loops in g starting at c.Elem, bail if there are any
-	{
-		seen := map[*gg.Vertex]bool{}
-		start := g.ValueVertex(elem)
-		var hasLoop func(v *gg.Vertex) bool
-		hasLoop = func(v *gg.Vertex) bool {
-			if seen[v] {
-				return v == start
-			}
-			seen[v] = true
-			for _, out := range v.Out {
-				if hasLoop(out.To) {
-					return true
-				}
-			}
-			return false
-		}
-		if hasLoop(start) {
-			return false
-		}
-	}
-
-	e.g = g
-	return true
-}
-
-// Solve uses the constraints which have been added to the engine to give a
-// possible solution. The given element is one which has been added to the
-// engine and whose value is known to be zero.
-func (e *Engine) Solve() map[string]int {
-	m := map[string]int{}
-	if len(e.g.ValueVertices()) == 0 {
-		return m
-	}
-
-	vElem := func(v *gg.Vertex) string {
-		return v.Value.V.(string)
-	}
-
-	// first the roots are determined to be the elements with no In edges, which
-	// _must_ exist since the graph presumably has no loops
-	var roots []*gg.Vertex
-	e.g.Iter(func(v *gg.Vertex) bool {
-		if len(v.In) == 0 {
-			roots = append(roots, v)
-			m[vElem(v)] = 0
-		}
-		return true
-	})
-
-	// sanity check
-	if len(roots) == 0 {
-		panic("no roots found in graph somehow")
-	}
-
-	// a vertex's value is then the length of the longest path from it to one of
-	// the roots
-	var walk func(*gg.Vertex, int)
-	walk = func(v *gg.Vertex, val int) {
-		if elem := vElem(v); val > m[elem] {
-			m[elem] = val
-		}
-		for _, out := range v.Out {
-			walk(out.To, val+1)
-		}
-	}
-	for _, root := range roots {
-		walk(root, 0)
-	}
-
-	return m
-}

gim/view/constraint/constraint_test.go

@@ -1,94 +0,0 @@
-package constraint
-
-import (
-	. "testing"
-
-	"github.com/stretchr/testify/assert"
-)
-
-func TestEngineAddConstraint(t *T) {
-	{
-		e := NewEngine()
-		assert.True(t, e.AddConstraint(Constraint{Elem: "0", LT: "1"}))
-		assert.True(t, e.AddConstraint(Constraint{Elem: "1", LT: "2"}))
-		assert.True(t, e.AddConstraint(Constraint{Elem: "-1", LT: "0"}))
-		assert.False(t, e.AddConstraint(Constraint{Elem: "1", LT: "0"}))
-		assert.False(t, e.AddConstraint(Constraint{Elem: "2", LT: "0"}))
-		assert.False(t, e.AddConstraint(Constraint{Elem: "2", LT: "-1"}))
-	}
-
-	{
-		e := NewEngine()
-		assert.True(t, e.AddConstraint(Constraint{Elem: "0", LT: "1"}))
-		assert.True(t, e.AddConstraint(Constraint{Elem: "0", LT: "2"}))
-		assert.True(t, e.AddConstraint(Constraint{Elem: "1", LT: "2"}))
-		assert.True(t, e.AddConstraint(Constraint{Elem: "2", LT: "3"}))
-	}
-}
-
-func TestEngineSolve(t *T) {
-	assertSolve := func(exp map[string]int, cc ...Constraint) {
-		e := NewEngine()
-		for _, c := range cc {
-			assert.True(t, e.AddConstraint(c), "c:%#v", c)
-		}
-		assert.Equal(t, exp, e.Solve())
-	}
-
-	// basic
-	assertSolve(
-		map[string]int{"a": 0, "b": 1, "c": 2},
-		Constraint{Elem: "a", LT: "b"},
-		Constraint{Elem: "b", LT: "c"},
-	)
-
-	// "triangle" graph
-	assertSolve(
-		map[string]int{"a": 0, "b": 1, "c": 2},
-		Constraint{Elem: "a", LT: "b"},
-		Constraint{Elem: "a", LT: "c"},
-		Constraint{Elem: "b", LT: "c"},
-	)
-
-	// "hexagon" graph
-	assertSolve(
-		map[string]int{"a": 0, "b": 1, "c": 1, "d": 2, "e": 2, "f": 3},
-		Constraint{Elem: "a", LT: "b"},
-		Constraint{Elem: "a", LT: "c"},
-		Constraint{Elem: "b", LT: "d"},
-		Constraint{Elem: "c", LT: "e"},
-		Constraint{Elem: "d", LT: "f"},
-		Constraint{Elem: "e", LT: "f"},
-	)
-
-	// "hexagon" with centerpoint graph
-	assertSolve(
-		map[string]int{"a": 0, "b": 1, "c": 1, "center": 2, "d": 3, "e": 3, "f": 4},
-		Constraint{Elem: "a", LT: "b"},
-		Constraint{Elem: "a", LT: "c"},
-		Constraint{Elem: "b", LT: "d"},
-		Constraint{Elem: "c", LT: "e"},
-		Constraint{Elem: "d", LT: "f"},
-		Constraint{Elem: "e", LT: "f"},
-
-		Constraint{Elem: "c", LT: "center"},
-		Constraint{Elem: "b", LT: "center"},
-		Constraint{Elem: "center", LT: "e"},
-		Constraint{Elem: "center", LT: "d"},
-	)
-
-	// multi-root, using two triangles which end up connecting
-	assertSolve(
-		map[string]int{"a": 0, "b": 1, "c": 2, "d": 0, "e": 1, "f": 2, "g": 3},
-		Constraint{Elem: "a", LT: "b"},
-		Constraint{Elem: "a", LT: "c"},
-		Constraint{Elem: "b", LT: "c"},
-
-		Constraint{Elem: "d", LT: "e"},
-		Constraint{Elem: "d", LT: "f"},
-		Constraint{Elem: "e", LT: "f"},
-
-		Constraint{Elem: "f", LT: "g"},
-	)
-
-}

gim/view/line.go

@@ -1,31 +0,0 @@
-package view
-
-import (
-	"github.com/mediocregopher/ginger/gim/geo"
-	"github.com/mediocregopher/ginger/gim/terminal"
-)
-
-type line struct {
-	from, to   *box
-	fromI, toI int
-	bodyBuf    *terminal.Buffer
-}
-
-func (l line) draw(buf *terminal.Buffer, flowDir, secFlowDir geo.XY) {
-	from, to := *(l.from), *(l.to)
-	start := from.rect().Edge(flowDir, secFlowDir)[0].Add(secFlowDir.Scale(l.fromI*2 + 1))
-	end := to.rect().Edge(flowDir.Inv(), secFlowDir)[0]
-	end = end.Add(flowDir.Inv())
-	end = end.Add(secFlowDir.Scale(l.toI*2 + 1))
-
-	buf.SetPos(start)
-	buf.WriteRune(terminal.SingleLine.Perpendicular(flowDir))
-	buf.DrawLine(start.Add(flowDir), end.Add(flowDir.Inv()), flowDir, terminal.SingleLine)
-	buf.SetPos(end)
-	buf.WriteRune(terminal.SingleLine.Arrow(flowDir))
-
-	// draw the body
-	if l.bodyBuf != nil {
-		buf.DrawBufferCentered(start.Midpoint(end), l.bodyBuf)
-	}
-}

gim/view/vertex.go

@@ -1,27 +0,0 @@
-package view
-
-import (
-	"github.com/mediocregopher/ginger/gim/geo"
-	"github.com/mediocregopher/ginger/gim/terminal"
-)
-
-type edge struct {
-	from, to   *vertex
-	tail, head rune // if empty do directional segment char
-	body       string
-	switchback bool
-
-	lineStyle terminal.LineStyle
-}
-
-type vertex struct {
-	coord, pos geo.XY
-	in, out    [][]*edge // top level is port index
-	body       string
-
-	// means it won't be drawn, and will be removed and have its in/out edges
-	// spliced together into a single edge.
-	ephemeral bool
-
-	lineStyle terminal.LineStyle // if zero value don't draw border
-}

gim/view/view.go

@@ -1,274 +0,0 @@
-// Package view implements rendering a graph to a terminal.
-//
-// Steps for rendering
-//
-//	- Preprocessing: Disjoin Graph into multiple Graphs, and decide how to
-//	  arrange them (maybe sort by number of vertices or number of edges (or the
-//	  sum of both) or something).
-//
-//	- Convert Graph into internal representation.
-//		- Still uses gg.Graph, but vertices and edge values are wrapped in types
-//		  internal to this package, and on which further mapping will be done.
-//		- Positions unknown at this point.
-//		- Junctions are converted to value vertices with set edge order.
-//		- Edges contain both their body and their tail/head rune.
-//
-//	- Find eligible "root" vertex, probably by one which has the fewest input
-//	  edges.
-//
-//	- Find cycles and reverse edges as needed.
-//		- The to/from vertices are reversed, as are the head/tail runes, so the
-//		  direction will appear consistent with the original graph
-//		- TODO this might not be necessary? Or at least may need to be modified.
-//		  In the paper this is done, but that algorithm allows for edges upward
-//		  from their tail, whereas this one doesn't. It might only be necessary
-//		  for the MST stuff, in which case this might only need to take place
-//		  within Positioning-Part1.
-//
-//	- Replace edge bodies with a vertex with a single input/output edge.
-//
-//	- Position all vertices
-//		- `coord` field on vertices used as row/column coordinates.
-//		- Positioning will be done with down being the primary direction and
-//		  right being the secondary direction.
-//		- Part 1) find vertical positions for all vertices (aka assign rows)
-//			- This step uses some fancy MST stuff as outlined by (TODO refer to
-//			  paper here).
-//		- Part 2) find horizontal positions within rows (aka assign columns)
-//			- Part of this will include creating ephemeral vertices where an
-//			  edge spans a row without having a vertex on it. These will be
-//			  removed as the final part of this step.
-//			- The jist of this step is to find vertex ordering which reduces
-//			  number of edge crossings between adjacent rows.
-//			- Some extra care is taken for cases where an edge's from vertex is
-//			  not a lower row than its to vertex.
-//				- This is an unavoidable case, as at the least a vertex may
-//				  connect to itself.
-//				- These edges will have their `switchback` field set to true.
-//				- For the purposes of calculating edge crossings these edges
-//				  should be ignored. During the absolute positioning and drawing
-//				  steps they will be accounted for and dealt with.
-//		- Part 3) row/column positions into terminal positions, which are
-//		  stored on the vertices in the `pos` field. Primary/secondary
-//		  direction are taken into account here.
-//
-//	- Post-processing: any additional absolute positioning and other formatting
-//	  given by the user for the Graph should be done here
-//
-//	- Draw vertices and their edges to buffer
-//		- At this point drawing vertices is easy. Edges is more complicated but
-//		  the start/end positions of each edge should already be known, so while
-//		  drawing may be complex it's not difficult.
-//
-package view
-
-import (
-	"sort"
-
-	"github.com/mediocregopher/ginger/gg"
-	"github.com/mediocregopher/ginger/gim/geo"
-	"github.com/mediocregopher/ginger/gim/terminal"
-	"github.com/mediocregopher/ginger/gim/view/constraint"
-)
-
-// View wraps a single Graph instance and a set of display options for it, and
-// generates renderable terminal output for it.
-type View struct {
-	g     *gg.Graph
-	start gg.Value // TODO shouldn't need this
-
-	primFlowDir, secFlowDir geo.XY
-}
-
-// New instantiates and returns a view around the given Graph instance, with
-// start indicating the value vertex to consider the "root" of the graph.
-//
-// Drawing is done by aligning the vertices into rows and columns in such a way
-// as to reduce edge crossings. primaryDir indicates the direction edges will
-// primarily be pointed in. For example, if it is geo.Down then adjacent
-// vertices will be arranged into columns.
-//
-// secondaryDir indicates the direction vertices should be arranged when they
-// end up in the same "rank" (e.g. when primaryDir is geo.Down, all vertices on
-// the same row will be the same "rank").
-//
-// A primaryDir/secondaryDir of either geo.Down/geo.Right or geo.Right/geo.Down
-// are recommended, but any combination of perpendicular directions is allowed.
-func New(g *gg.Graph, start gg.Value, primaryDir, secondaryDir geo.XY) *View {
-	return &View{
-		g:           g,
-		start:       start,
-		primFlowDir: primaryDir,
-		secFlowDir:  secondaryDir,
-	}
-}
-
-// Draw renders and draws the View's Graph to the Buffer.
-func (view *View) Draw(buf *terminal.Buffer) {
-	relPos, _, secSol := posSolve(view.g)
-
-	// create boxes
-	var boxes []*box
-	boxesM := map[*box]*gg.Vertex{}
-	boxesMr := map[*gg.Vertex]*box{}
-	const (
-		primPadding = 5
-		secPadding  = 1
-	)
-	var primPos int
-	for _, vv := range relPos {
-		var primBoxes []*box // boxes on just this level
-		var maxPrim int
-		var secPos int
-		for _, v := range vv {
-			primVec := view.primFlowDir.Scale(primPos)
-			secVec := view.secFlowDir.Scale(secPos)
-
-			b := boxFromVertex(v, view.primFlowDir)
-			b.topLeft = primVec.Add(secVec)
-			boxes = append(boxes, &b)
-			primBoxes = append(primBoxes, &b)
-			boxesM[&b] = v
-			boxesMr[v] = &b
-
-			bSize := b.rect().Size
-			primBoxLen := bSize.Mul(view.primFlowDir).Len()
-			secBoxLen := bSize.Mul(view.secFlowDir).Len()
-			if primBoxLen > maxPrim {
-				maxPrim = primBoxLen
-			}
-			secPos += secBoxLen + secPadding
-		}
-		for _, b := range primBoxes {
-			b.topLeft = b.topLeft.Add(view.primFlowDir.Scale(primPos))
-		}
-		primPos += maxPrim + primPadding
-	}
-
-	// maps a vertex to all of its to edges, sorted by secSol
-	findFromIM := map[*gg.Vertex][]gg.Edge{}
-	// returns the index of this edge in from's Out
-	findFromI := func(from *gg.Vertex, e gg.Edge) int {
-		edges, ok := findFromIM[from]
-		if !ok {
-			edges = make([]gg.Edge, len(from.Out))
-			copy(edges, from.Out)
-			sort.Slice(edges, func(i, j int) bool {
-				// TODO if two edges go to the same vertex, how are they sorted?
-				return secSol[edges[i].To.ID] < secSol[edges[j].To.ID]
-			})
-			findFromIM[from] = edges
-		}
-
-		for i, fe := range edges {
-			if fe == e {
-				return i
-			}
-		}
-		panic("edge not found in from.Out")
-	}
-
-	// create lines
-	var lines []line
-	for _, b := range boxes {
-		v := boxesM[b]
-		for i, e := range v.In {
-			bFrom := boxesMr[e.From]
-			fromI := findFromI(e.From, e)
-			buf := terminal.NewBuffer()
-			buf.WriteString(e.Value.V.(string))
-			lines = append(lines, line{
-				from:    bFrom,
-				fromI:   fromI,
-				to:      b,
-				toI:     i,
-				bodyBuf: buf,
-			})
-		}
-	}
-
-	// actually draw the boxes and lines
-	for _, b := range boxes {
-		b.draw(buf)
-	}
-	for _, line := range lines {
-		line.draw(buf, view.primFlowDir, view.secFlowDir)
-	}
-}
-
-// "Solves" vertex position by detemining relative positions of vertices in
-// primary and secondary directions (independently), with relative positions
-// being described by "levels", where multiple vertices can occupy one level.
-//
-// Primary determines relative position in the primary direction by trying
-// to place vertices before their outs and after their ins.
-//
-// Secondary determines relative position in the secondary direction by
-// trying to place vertices relative to vertices they share an edge with in
-// the order that the edges appear on the shared node.
-func posSolve(g *gg.Graph) ([][]*gg.Vertex, map[string]int, map[string]int) {
-	primEng := constraint.NewEngine()
-	secEng := constraint.NewEngine()
-
-	strM := g.ByID()
-	for _, v := range strM {
-		var prevIn *gg.Vertex
-		for _, e := range v.In {
-			primEng.AddConstraint(constraint.Constraint{
-				Elem: e.From.ID,
-				LT:   v.ID,
-			})
-			if prevIn != nil {
-				secEng.AddConstraint(constraint.Constraint{
-					Elem: prevIn.ID,
-					LT:   e.From.ID,
-				})
-			}
-			prevIn = e.From
-		}
-
-		var prevOut *gg.Vertex
-		for _, e := range v.Out {
-			if prevOut == nil {
-				continue
-			}
-			secEng.AddConstraint(constraint.Constraint{
-				Elem: prevOut.ID,
-				LT:   e.To.ID,
-			})
-			prevOut = e.To
-		}
-	}
-	prim := primEng.Solve()
-	sec := secEng.Solve()
-
-	// determine maximum primary level
-	var maxPrim int
-	for _, lvl := range prim {
-		if lvl > maxPrim {
-			maxPrim = lvl
-		}
-	}
-
-	outStr := make([][]string, maxPrim+1)
-	for v, lvl := range prim {
-		outStr[lvl] = append(outStr[lvl], v)
-	}
-
-	// sort each primary level
-	for _, vv := range outStr {
-		sort.Slice(vv, func(i, j int) bool {
-			return sec[vv[i]] < sec[vv[j]]
-		})
-	}
-
-	// convert to vertices
-	out := make([][]*gg.Vertex, len(outStr))
-	for i, vv := range outStr {
-		out[i] = make([]*gg.Vertex, len(outStr[i]))
-		for j, v := range vv {
-			out[i][j] = strM[v]
-		}
-	}
-	return out, prim, sec
-}

go.mod

@@ -0,0 +1,14 @@
+module code.betamike.com/mediocregopher/ginger
+
+go 1.18
+
+require (
+	github.com/stretchr/testify v1.7.0
+	golang.org/x/exp v0.0.0-20231006140011-7918f672742d
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.0 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c // indirect
+)

go.sum

@@ -0,0 +1,13 @@
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+golang.org/x/exp v0.0.0-20231006140011-7918f672742d h1:jtJma62tbqLibJ5sFQz8bKtEM8rJBtfilJ2qTU199MI=
+golang.org/x/exp v0.0.0-20231006140011-7918f672742d/go.mod h1:ldy0pHrwJyGW56pPQzzkH36rKxoZW1tw7ZJpeKx+hdo=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

graph/graph.go

@@ -0,0 +1,432 @@
+// Package graph implements a generic directed graph type, with support for
+// tuple vertices in addition to traditional "value" vertices.
+package graph
+
+import (
+	"fmt"
+	"strings"
+)
+
+// Value is any value which can be stored within a Graph. Values should be
+// considered immutable, ie once used with the graph package their internal
+// value does not change.
+type Value interface {
+	Equal(Value) bool
+	String() string
+}
+
+// OpenEdge consists of the edge value (E) and source vertex value (V) of an
+// edge in a Graph. When passed into the AddValueIn method a full edge is
+// created. An OpenEdge can also be sourced from a tuple vertex, whose value is
+// an ordered set of OpenEdges of this same type.
+type OpenEdge[E, V Value] struct {
+	val *V
+	tup []*OpenEdge[E, V]
+
+	edgeVal E
+}
+
+func (oe *OpenEdge[E, V]) equal(oe2 *OpenEdge[E, V]) bool {
+	if !oe.edgeVal.Equal(oe2.edgeVal) {
+		return false
+	}
+
+	if oe.val != nil {
+		return oe2.val != nil && (*oe.val).Equal(*oe2.val)
+	}
+
+	if len(oe.tup) != len(oe2.tup) {
+		return false
+	}
+
+	for i := range oe.tup {
+		if !oe.tup[i].equal(oe2.tup[i]) {
+			return false
+		}
+	}
+
+	return true
+}
+
+func (oe *OpenEdge[E, V]) String() string {
+
+	vertexType := "tup"
+
+	var fromStr string
+
+	if oe.val != nil {
+
+		vertexType = "val"
+		fromStr = (*oe.val).String()
+
+	} else {
+
+		strs := make([]string, len(oe.tup))
+
+		for i := range oe.tup {
+			strs[i] = oe.tup[i].String()
+		}
+
+		fromStr = fmt.Sprintf("[%s]", strings.Join(strs, ", "))
+	}
+
+	return fmt.Sprintf("%s(%s, %s)", vertexType, fromStr, oe.edgeVal.String())
+}
+
+// WithEdgeValue returns a copy of the OpenEdge with the given Value replacing
+// the previous edge value.
+//
+// NOTE I _think_ this can be factored out once Graph is genericized.
+func (oe *OpenEdge[E, V]) WithEdgeValue(val E) *OpenEdge[E, V] {
+	oeCp := *oe
+	oeCp.edgeVal = val
+	return &oeCp
+}
+
+// EdgeValue returns the Value which lies on the edge itself.
+func (oe OpenEdge[E, V]) EdgeValue() E {
+	return oe.edgeVal
+}
+
+// FromValue returns the Value from which the OpenEdge was created via ValueOut,
+// or false if it wasn't created via ValueOut.
+func (oe OpenEdge[E, V]) FromValue() (V, bool) {
+	if oe.val == nil {
+		var zero V
+		return zero, false
+	}
+
+	return *oe.val, true
+}
+
+// FromTuple returns the tuple of OpenEdges from which the OpenEdge was created
+// via TupleOut, or false if it wasn't created via TupleOut.
+func (oe OpenEdge[E, V]) FromTuple() ([]*OpenEdge[E, V], bool) {
+	if oe.val != nil {
+		return nil, false
+	}
+
+	return oe.tup, true
+}
+
+// ValueOut creates a OpenEdge which, when used to construct a Graph, represents
+// an edge (with edgeVal attached to it) coming from the vertex containing val.
+func ValueOut[E, V Value](edgeVal E, val V) *OpenEdge[E, V] {
+	return &OpenEdge[E, V]{
+		val:     &val,
+		edgeVal: edgeVal,
+	}
+}
+
+// TupleOut creates an OpenEdge which, when used to construct a Graph,
+// represents an edge (with edgeVal attached to it) coming from the vertex
+// comprised of the given ordered-set of input edges.
+func TupleOut[E, V Value](edgeVal E, ins ...*OpenEdge[E, V]) *OpenEdge[E, V] {
+
+	if len(ins) == 1 {
+
+		var (
+			zero E
+			in   = ins[0]
+		)
+
+		if edgeVal.Equal(zero) {
+			return in
+		}
+
+		if in.edgeVal.Equal(zero) {
+			return in.WithEdgeValue(edgeVal)
+		}
+
+	}
+
+	return &OpenEdge[E, V]{
+		tup:     ins,
+		edgeVal: edgeVal,
+	}
+}
+
+type graphValueIn[E, V Value] struct {
+	val  V
+	edge *OpenEdge[E, V]
+}
+
+func (valIn graphValueIn[E, V]) equal(valIn2 graphValueIn[E, V]) bool {
+	return valIn.val.Equal(valIn2.val) && valIn.edge.equal(valIn2.edge)
+}
+
+// Graph is an immutable container of a set of vertices. The Graph keeps track
+// of all Values which terminate an OpenEdge. E indicates the type of edge
+// values, while V indicates the type of vertex values.
+//
+// NOTE The current implementation of Graph is incredibly inefficient, there's
+// lots of O(N) operations, unnecessary copying on changes, and duplicate data
+// in memory.
+type Graph[E, V Value] struct {
+	edges  []*OpenEdge[E, V]
+	valIns []graphValueIn[E, V]
+}
+
+func (g *Graph[E, V]) cp() *Graph[E, V] {
+	cp := &Graph[E, V]{
+		edges:  make([]*OpenEdge[E, V], len(g.edges)),
+		valIns: make([]graphValueIn[E, V], len(g.valIns)),
+	}
+	copy(cp.edges, g.edges)
+	copy(cp.valIns, g.valIns)
+	return cp
+}
+
+func (g *Graph[E, V]) String() string {
+
+	var strs []string
+
+	for _, valIn := range g.valIns {
+		strs = append(
+			strs,
+			fmt.Sprintf("valIn(%s, %s)", valIn.edge.String(), valIn.val.String()),
+		)
+	}
+
+	return fmt.Sprintf("graph(%s)", strings.Join(strs, ", "))
+}
+
+// NOTE this method is used more for its functionality than for any performance
+// reasons... it's incredibly inefficient in how it deduplicates edges, but by
+// doing the deduplication we enable the graph map operation to work correctly.
+func (g *Graph[E, V]) dedupeEdge(edge *OpenEdge[E, V]) *OpenEdge[E, V] {
+
+	// check if there's an existing edge which is fully equivalent in the graph
+	// already, and if so return that.
+	for i := range g.edges {
+		if g.edges[i].equal(edge) {
+			return g.edges[i]
+		}
+	}
+
+	// if this edge is a value edge then there's nothing else to do, return it.
+	if _, ok := edge.FromValue(); ok {
+		return edge
+	}
+
+	// this edge is a tuple edge, it's possible that one of its sub-edges is
+	// already in the graph. dedupe each sub-edge individually.
+
+	tupEdges := make([]*OpenEdge[E, V], len(edge.tup))
+
+	for i := range edge.tup {
+		tupEdges[i] = g.dedupeEdge(edge.tup[i])
+	}
+
+	return TupleOut(edge.EdgeValue(), tupEdges...)
+}
+
+// ValueIns returns, if any, all OpenEdges which lead to the given Value in the
+// Graph (ie, all those added via AddValueIn).
+//
+// The returned slice should not be modified.
+//
+// TODO better name might be OpenEdgesInto.
+func (g *Graph[E, V]) ValueIns(val Value) []*OpenEdge[E, V] {
+
+	var edges []*OpenEdge[E, V]
+
+	for _, valIn := range g.valIns {
+		if valIn.val.Equal(val) {
+			edges = append(edges, valIn.edge)
+		}
+	}
+
+	return edges
+}
+
+// AddValueIn takes a OpenEdge and connects it to the Value vertex containing
+// val, returning the new Graph which reflects that connection.
+func (g *Graph[E, V]) AddValueIn(val V, oe *OpenEdge[E, V]) *Graph[E, V] {
+
+	valIn := graphValueIn[E, V]{
+		val:  val,
+		edge: oe,
+	}
+
+	for i := range g.valIns {
+		if g.valIns[i].equal(valIn) {
+			return g
+		}
+	}
+
+	valIn.edge = g.dedupeEdge(valIn.edge)
+
+	g = g.cp()
+	g.valIns = append(g.valIns, valIn)
+
+	return g
+}
+
+// AllValueIns returns all values which have had incoming edges added to them
+// using AddValueIn.
+func (g *Graph[E, V]) AllValueIns() []V {
+	vals := make([]V, len(g.valIns))
+	for i := range g.valIns {
+		vals[i] = g.valIns[i].val
+	}
+	return vals
+}
+
+// Equal returns whether or not the two Graphs are equivalent in value.
+func (g *Graph[E, V]) Equal(g2 *Graph[E, V]) bool {
+
+	if len(g.valIns) != len(g2.valIns) {
+		return false
+	}
+
+outer:
+	for _, valIn := range g.valIns {
+
+		for _, valIn2 := range g2.valIns {
+
+			if valIn.equal(valIn2) {
+				continue outer
+			}
+		}
+
+		return false
+	}
+
+	return true
+}
+
+func mapReduce[Ea, Va Value, Vb any](
+	root *OpenEdge[Ea, Va],
+	mapVal func(Va) (Vb, error),
+	reduceEdge func(*OpenEdge[Ea, Va], []Vb) (Vb, error),
+) (
+	Vb, error,
+) {
+
+	if valA, ok := root.FromValue(); ok {
+
+		valB, err := mapVal(valA)
+
+		if err != nil {
+			var zero Vb
+			return zero, err
+		}
+
+		return reduceEdge(root, []Vb{valB})
+	}
+
+	tupA, _ := root.FromTuple()
+
+	valsB := make([]Vb, len(tupA))
+
+	for i := range tupA {
+
+		valB, err := mapReduce[Ea, Va, Vb](
+			tupA[i], mapVal, reduceEdge,
+		)
+
+		if err != nil {
+			var zero Vb
+			return zero, err
+		}
+
+		valsB[i] = valB
+	}
+
+	return reduceEdge(root, valsB)
+}
+
+type mappedVal[Va Value, Vb any] struct {
+	valA Va
+	valB Vb // result
+}
+
+type reducedEdge[Ea, Va Value, Vb any] struct {
+	edgeA *OpenEdge[Ea, Va]
+	valB  Vb // result
+}
+
+// MapReduce recursively computes a resultant Value of type Vb from an
+// OpenEdge[Ea, Va].
+//
+// Tuple edges which are encountered will have Reduce called on each OpenEdge
+// branch of the tuple, to obtain a Vb for each branch. The edge value of the
+// tuple edge (Ea) and the just obtained Vbs are then passed to reduceEdge to
+// obtain a Vb for that edge.
+//
+// The values of value edges (Va) which are encountered are mapped to Vb using
+// the mapVal function. The edge value of those value edges (Ea) and the just
+// obtained Vb value are then passed to reduceEdge to obtain a Vb for that edge.
+//
+// If either the map or reduce function returns an error then processing is
+// immediately cancelled and that error is returned directly.
+//
+// If a value or edge is connected to multiple times within the root OpenEdge it
+// will only be mapped/reduced a single time, and the result of that single
+// map/reduction will be passed to each dependant operation.
+func MapReduce[Ea, Va Value, Vb any](
+	root *OpenEdge[Ea, Va],
+	mapVal func(Va) (Vb, error),
+	reduceEdge func(Ea, []Vb) (Vb, error),
+) (
+	Vb, error,
+) {
+
+	var (
+		zeroB Vb
+
+		// we use these to memoize reductions on values and edges, so a
+		// reduction is only performed a single time for each value/edge.
+		//
+		// NOTE this is not implemented very efficiently.
+		mappedVals   []mappedVal[Va, Vb]
+		reducedEdges []reducedEdge[Ea, Va, Vb]
+	)
+
+	return mapReduce[Ea, Va, Vb](
+		root,
+		func(valA Va) (Vb, error) {
+
+			for _, mappedVal := range mappedVals {
+				if mappedVal.valA.Equal(valA) {
+					return mappedVal.valB, nil
+				}
+			}
+
+			valB, err := mapVal(valA)
+
+			if err != nil {
+				return zeroB, err
+			}
+
+			mappedVals = append(mappedVals, mappedVal[Va, Vb]{
+				valA: valA,
+				valB: valB,
+			})
+
+			return valB, nil
+		},
+		func(edgeA *OpenEdge[Ea, Va], valBs []Vb) (Vb, error) {
+
+			for _, reducedEdge := range reducedEdges {
+				if reducedEdge.edgeA.equal(edgeA) {
+					return reducedEdge.valB, nil
+				}
+			}
+
+			valB, err := reduceEdge(edgeA.EdgeValue(), valBs)
+
+			if err != nil {
+				return zeroB, err
+			}
+
+			reducedEdges = append(reducedEdges, reducedEdge[Ea, Va, Vb]{
+				edgeA: edgeA,
+				valB:  valB,
+			})
+
+			return valB, nil
+		},
+	)
+}

graph/graph_test.go

@@ -0,0 +1,268 @@
+package graph
+
+import (
+	"errors"
+	"fmt"
+	"strconv"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type S string
+
+func (s S) Equal(s2 Value) bool { return s == s2.(S) }
+
+func (s S) String() string { return string(s) }
+
+type I int
+
+func (i I) Equal(i2 Value) bool { return i == i2.(I) }
+
+func (i I) String() string { return strconv.Itoa(int(i)) }
+
+func TestEqual(t *testing.T) {
+
+	var (
+		zeroValue S
+		zeroGraph = new(Graph[S, S])
+	)
+
+	tests := []struct {
+		a, b *Graph[S, S]
+		exp  bool
+	}{
+		{
+			a:   zeroGraph,
+			b:   zeroGraph,
+			exp: true,
+		},
+		{
+			a:   zeroGraph,
+			b:   zeroGraph.AddValueIn("out", ValueOut[S, S]("incr", "in")),
+			exp: false,
+		},
+		{
+			a:   zeroGraph.AddValueIn("out", ValueOut[S, S]("incr", "in")),
+			b:   zeroGraph.AddValueIn("out", ValueOut[S, S]("incr", "in")),
+			exp: true,
+		},
+		{
+			a: zeroGraph.AddValueIn("out", ValueOut[S, S]("incr", "in")),
+			b: zeroGraph.AddValueIn("out", TupleOut[S, S](
+				"add",
+				ValueOut[S, S]("ident", "in"),
+				ValueOut[S, S]("ident", "1"),
+			)),
+			exp: false,
+		},
+		{
+			// tuples are different order
+			a: zeroGraph.AddValueIn("out", TupleOut[S, S](
+				"add",
+				ValueOut[S, S]("ident", "1"),
+				ValueOut[S, S]("ident", "in"),
+			)),
+			b: zeroGraph.AddValueIn("out", TupleOut[S, S](
+				"add",
+				ValueOut[S, S]("ident", "in"),
+				ValueOut[S, S]("ident", "1"),
+			)),
+			exp: false,
+		},
+		{
+			// tuple with no edge value and just a single input edge should be
+			// equivalent to just that edge.
+			a: zeroGraph.AddValueIn("out", TupleOut[S, S](
+				zeroValue,
+				ValueOut[S, S]("ident", "1"),
+			)),
+			b:   zeroGraph.AddValueIn("out", ValueOut[S, S]("ident", "1")),
+			exp: true,
+		},
+		{
+			// tuple with an edge value and just a single input edge that has no
+			// edgeVal should be equivalent to just that edge with the tuple's
+			// edge value.
+			a: zeroGraph.AddValueIn("out", TupleOut[S, S](
+				"ident",
+				ValueOut[S, S](zeroValue, "1"),
+			)),
+			b:   zeroGraph.AddValueIn("out", ValueOut[S, S]("ident", "1")),
+			exp: true,
+		},
+		{
+			a: zeroGraph.
+				AddValueIn("out", ValueOut[S, S]("incr", "in")).
+				AddValueIn("out2", ValueOut[S, S]("incr2", "in2")),
+			b: zeroGraph.
+				AddValueIn("out", ValueOut[S, S]("incr", "in")),
+			exp: false,
+		},
+		{
+			a: zeroGraph.
+				AddValueIn("out", ValueOut[S, S]("incr", "in")).
+				AddValueIn("out2", ValueOut[S, S]("incr2", "in2")),
+			b: zeroGraph.
+				AddValueIn("out", ValueOut[S, S]("incr", "in")).
+				AddValueIn("out2", ValueOut[S, S]("incr2", "in2")),
+			exp: true,
+		},
+		{
+			// order of value ins shouldn't matter
+			a: zeroGraph.
+				AddValueIn("out", ValueOut[S, S]("incr", "in")).
+				AddValueIn("out2", ValueOut[S, S]("incr2", "in2")),
+			b: zeroGraph.
+				AddValueIn("out2", ValueOut[S, S]("incr2", "in2")).
+				AddValueIn("out", ValueOut[S, S]("incr", "in")),
+			exp: true,
+		},
+	}
+
+	for i, test := range tests {
+		t.Run(strconv.Itoa(i), func(t *testing.T) {
+			assert.Equal(t, test.exp, test.a.Equal(test.b))
+		})
+	}
+}
+
+type mapReduceTestEdge struct {
+	name string
+	fn   func([]int) int
+	done bool
+}
+
+func (e *mapReduceTestEdge) Equal(e2i Value) bool {
+
+	e2, _ := e2i.(*mapReduceTestEdge)
+
+	if e == nil || e2 == nil {
+		return e == e2
+	}
+
+	return e.name == e2.name
+}
+
+func (e *mapReduceTestEdge) String() string {
+	return e.name
+}
+
+func (e *mapReduceTestEdge) do(ii []int) int {
+
+	if e.done {
+		panic(fmt.Sprintf("%q already done", e.name))
+	}
+
+	e.done = true
+
+	return e.fn(ii)
+}
+
+func TestMapReduce(t *testing.T) {
+
+	type (
+		Va   = I
+		Vb   = int
+		Ea   = *mapReduceTestEdge
+		edge = OpenEdge[Ea, Va]
+	)
+
+	var (
+		zeroVb Vb
+	)
+
+	vOut := func(edge Ea, val Va) *edge {
+		return ValueOut[Ea, Va](edge, val)
+	}
+
+	tOut := func(edge Ea, ins ...*edge) *edge {
+		return TupleOut[Ea, Va](edge, ins...)
+	}
+
+	add := func() *mapReduceTestEdge {
+		return &mapReduceTestEdge{
+			name: "add",
+			fn: func(ii []int) int {
+				var n int
+				for _, i := range ii {
+					n += i
+				}
+				return n
+			},
+		}
+	}
+
+	mul := func() *mapReduceTestEdge {
+		return &mapReduceTestEdge{
+			name: "mul",
+			fn: func(ii []int) int {
+				n := 1
+				for _, i := range ii {
+					n *= i
+				}
+				return n
+			},
+		}
+	}
+
+	mapVal := func(valA Va) (Vb, error) {
+		return Vb(valA * 10), nil
+	}
+
+	reduceEdge := func(edgeA Ea, valBs []Vb) (Vb, error) {
+
+		if edgeA == nil {
+
+			if len(valBs) == 1 {
+				return valBs[0], nil
+			}
+
+			return zeroVb, errors.New("tuple edge must have edge value")
+		}
+
+		return edgeA.do(valBs), nil
+	}
+
+	tests := []struct {
+		in  *edge
+		exp int
+	}{
+		{
+			in:  vOut(nil, 1),
+			exp: 10,
+		},
+		{
+			in:  vOut(add(), 1),
+			exp: 10,
+		},
+		{
+			in: tOut(
+				add(),
+				vOut(nil, 1),
+				vOut(add(), 2),
+				vOut(mul(), 3),
+			),
+			exp: 60,
+		},
+		{
+			// duplicate edges and values getting used twice, each should only
+			// get eval'd once
+			in: tOut(
+				add(),
+				tOut(add(), vOut(nil, 1), vOut(nil, 2)),
+				tOut(add(), vOut(nil, 1), vOut(nil, 2)),
+				tOut(add(), vOut(nil, 3), vOut(nil, 3)),
+			),
+			exp: 120,
+		},
+	}
+
+	for i, test := range tests {
+		t.Run(strconv.Itoa(i), func(t *testing.T) {
+			got, err := MapReduce(test.in, mapVal, reduceEdge)
+			assert.NoError(t, err)
+			assert.Equal(t, test.exp, got)
+		})
+	}
+}

lang/lang.go

@@ -1,118 +0,0 @@
-package lang
-
-import (
-	"fmt"
-	"reflect"
-	"strings"
-)
-
-// Commonly used Terms
-var (
-	// Language structure types
-	AAtom  = Atom("atom")
-	AConst = Atom("const")
-	ATuple = Atom("tup")
-	AList  = Atom("list")
-
-	// Match shortcuts
-	AUnder    = Atom("_")
-	TDblUnder = Tuple{AUnder, AUnder}
-)
-
-// Term is a unit of language which carries some meaning. Some Terms are
-// actually comprised of multiple sub-Terms.
-type Term interface {
-	fmt.Stringer // for debugging
-
-	// Type returns a Term which describes the type of this Term, i.e.  the
-	// components this Term is comprised of.
-	Type() Term
-}
-
-// Equal returns whether or not two Terms are of equal value
-func Equal(t1, t2 Term) bool {
-	return reflect.DeepEqual(t1, t2)
-}
-
-////////////////////////////////////////////////////////////////////////////////
-
-// Atom is a constant with no other meaning than that it can be equal or not
-// equal to another Atom.
-type Atom string
-
-func (a Atom) String() string {
-	return string(a)
-}
-
-// Type implements the method for Term
-func (a Atom) Type() Term {
-	return AAtom
-}
-
-////////////////////////////////////////////////////////////////////////////////
-
-// Const is a constant whose meaning depends on the context in which it is used
-type Const string
-
-func (a Const) String() string {
-	return string(a)
-}
-
-// Type implements the method for Term
-func (a Const) Type() Term {
-	return AConst
-}
-
-////////////////////////////////////////////////////////////////////////////////
-
-// Tuple is a compound Term of zero or more sub-Terms, each of which may have a
-// different Type. Both the length of the Tuple and the Type of each of it's
-// sub-Terms are components in the Tuple's Type.
-type Tuple []Term
-
-func (t Tuple) String() string {
-	ss := make([]string, len(t))
-	for i := range t {
-		ss[i] = t[i].String()
-	}
-	return "(" + strings.Join(ss, " ") + ")"
-}
-
-// Type implements the method for Term
-func (t Tuple) Type() Term {
-	tt := make(Tuple, len(t))
-	for i := range t {
-		tt[i] = t[i].Type()
-	}
-	return Tuple{ATuple, tt}
-}
-
-////////////////////////////////////////////////////////////////////////////////
-
-type list struct {
-	typ Term
-	ll  []Term
-}
-
-// List is a compound Term of zero or more sub-Terms, each of which must have
-// the same Type (the one given as the first argument to this function). Only
-// the Type of the sub-Terms is a component in the List's Type.
-func List(typ Term, elems ...Term) Term {
-	return list{
-		typ: typ,
-		ll:  elems,
-	}
-}
-
-func (l list) String() string {
-	ss := make([]string, len(l.ll))
-	for i := range l.ll {
-		ss[i] = l.ll[i].String()
-	}
-	return "[" + strings.Join(ss, " ") + "]"
-}
-
-// Type implements the method for Term
-func (l list) Type() Term {
-	return Tuple{AList, l.typ}
-}

lang/match.go

@@ -1,54 +0,0 @@
-package lang
-
-import "fmt"
-
-// Match is used to pattern match an arbitrary Term against a pattern. A pattern
-// is a 2-tuple of the type (as an atom, e.g. AAtom, AConst) and a matching
-// value.
-//
-// If the value is AUnder the pattern will match all Terms of the type,
-// regardless of their value. If the pattern's type and value are both AUnder
-// the pattern will match all Terms.
-//
-// If the pattern's value is a Tuple or a List, each of its values will be used
-// as a sub-pattern to match against the corresponding value in the value.
-func Match(pat Tuple, t Term) bool {
-	if len(pat) != 2 {
-		return false
-	}
-	pt, pv := pat[0], pat[1]
-
-	switch pt {
-	case AAtom:
-		a, ok := t.(Atom)
-		return ok && (Equal(pv, AUnder) || Equal(pv, a))
-	case AConst:
-		c, ok := t.(Const)
-		return ok && (Equal(pv, AUnder) || Equal(pv, c))
-	case ATuple:
-		tt, ok := t.(Tuple)
-		if !ok {
-			return false
-		} else if Equal(pv, AUnder) {
-			return true
-		}
-
-		pvt := pv.(Tuple)
-		if len(tt) != len(pvt) {
-			return false
-		}
-		for i := range tt {
-			pvti, ok := pvt[i].(Tuple)
-			if !ok || !Match(pvti, tt[i]) {
-				return false
-			}
-		}
-		return true
-	case AList:
-		panic("TODO")
-	case AUnder:
-		return true
-	default:
-		panic(fmt.Sprintf("unknown type %T", pt))
-	}
-}

lang/match_test.go

@@ -1,66 +0,0 @@
-package lang
-
-import (
-	. "testing"
-
-	"github.com/stretchr/testify/assert"
-)
-
-func TestMatch(t *T) {
-	pat := func(typ, val Term) Tuple {
-		return Tuple{typ, val}
-	}
-
-	tests := []struct {
-		pattern Tuple
-		t       Term
-		exp     bool
-	}{
-		{pat(AAtom, Atom("foo")), Atom("foo"), true},
-		{pat(AAtom, Atom("foo")), Atom("bar"), false},
-		{pat(AAtom, Atom("foo")), Const("foo"), false},
-		{pat(AAtom, Atom("foo")), Tuple{Atom("a"), Atom("b")}, false},
-		{pat(AAtom, Atom("_")), Atom("bar"), true},
-		{pat(AAtom, Atom("_")), Const("bar"), false},
-
-		{pat(AConst, Const("foo")), Const("foo"), true},
-		{pat(AConst, Const("foo")), Atom("foo"), false},
-		{pat(AConst, Const("foo")), Const("bar"), false},
-		{pat(AConst, Atom("_")), Const("bar"), true},
-		{pat(AConst, Atom("_")), Atom("foo"), false},
-
-		{
-			pat(ATuple, Tuple{
-				pat(AAtom, Atom("foo")),
-				pat(AAtom, Atom("bar")),
-			}),
-			Tuple{Atom("foo"), Atom("bar")},
-			true,
-		},
-		{
-			pat(ATuple, Tuple{
-				pat(AAtom, Atom("_")),
-				pat(AAtom, Atom("bar")),
-			}),
-			Tuple{Atom("foo"), Atom("bar")},
-			true,
-		},
-		{
-			pat(ATuple, Tuple{
-				pat(AAtom, Atom("_")),
-				pat(AAtom, Atom("_")),
-				pat(AAtom, Atom("_")),
-			}),
-			Tuple{Atom("foo"), Atom("bar")},
-			false,
-		},
-
-		{pat(AUnder, AUnder), Atom("foo"), true},
-		{pat(AUnder, AUnder), Const("foo"), true},
-		{pat(AUnder, AUnder), Tuple{Atom("a"), Atom("b")}, true},
-	}
-
-	for _, testCase := range tests {
-		assert.Equal(t, testCase.exp, Match(testCase.pattern, testCase.t), "%#v", testCase)
-	}
-}

lexer/lexer.go

@@ -1,349 +0,0 @@
-package lexer
-
-import (
-	"bufio"
-	"bytes"
-	"errors"
-	"fmt"
-	"io"
-	"strings"
-)
-
-// TokenType indicates the type of a token
-type TokenType string
-
-// Different token types
-const (
-	Identifier TokenType = "identifier"
-
-	// Punctuation are tokens which connect two other tokens
-	Punctuation TokenType = "punctuation"
-
-	// Wrapper wraps one or more tokens
-	Wrapper TokenType = "wrapper"
-	String  TokenType = "string"
-	Err     TokenType = "err"
-	EOF     TokenType = "eof"
-)
-
-// Token is a single token which has been read in. All Tokens have a non-empty
-// Val
-type Token struct {
-	TokenType
-	Val      string
-	Row, Col int
-}
-
-// Equal returns whether two tokens are of equal type and value
-func (tok Token) Equal(tok2 Token) bool {
-	return tok.TokenType == tok2.TokenType && tok.Val == tok2.Val
-}
-
-// Err returns the error contained by the token, if any. Only returns non-nil if
-// TokenType is Err or EOF
-func (tok Token) Err() error {
-	if tok.TokenType == Err || tok.TokenType == EOF {
-		return fmt.Errorf("[line:%d col:%d] %s", tok.Row, tok.Col, tok.Val)
-	}
-	return nil
-}
-
-func (tok Token) String() string {
-	var typ string
-	switch tok.TokenType {
-	case Identifier:
-		typ = "ident"
-	case Punctuation:
-		typ = "punct"
-	case String:
-		typ = "str"
-	case Err, EOF:
-		typ = "err"
-	}
-	return fmt.Sprintf("%s(%q)", typ, tok.Val)
-}
-
-type lexerFn func(*Lexer) lexerFn
-
-// Lexer is used to read in ginger tokens from a source. HasNext() must be
-// called before every call to Next()
-type Lexer struct {
-	in  *bufio.Reader
-	out *bytes.Buffer
-	cur lexerFn
-
-	next []Token
-
-	row, col       int
-	absRow, absCol int
-}
-
-// New returns a Lexer which will read tokens from the given source.
-func New(r io.Reader) *Lexer {
-	return &Lexer{
-		in:  bufio.NewReader(r),
-		out: new(bytes.Buffer),
-		cur: lex,
-
-		row: -1,
-		col: -1,
-	}
-}
-
-func (l *Lexer) emit(t TokenType) {
-	str := l.out.String()
-	if str == "" {
-		panic("cannot emit empty token")
-	}
-	l.out.Reset()
-
-	l.emitTok(Token{
-		TokenType: t,
-		Val:       str,
-		Row:       l.row,
-		Col:       l.col,
-	})
-}
-
-func (l *Lexer) emitErr(err error) {
-	tok := Token{
-		TokenType: Err,
-		Val:       err.Error(),
-		Row:       l.absRow,
-		Col:       l.absCol,
-	}
-	if err == io.EOF {
-		tok.TokenType = EOF
-	}
-	l.emitTok(tok)
-}
-
-func (l *Lexer) emitTok(tok Token) {
-	l.next = append(l.next, tok)
-	l.row = -1
-	l.col = -1
-}
-
-func (l *Lexer) readRune() (rune, error) {
-	r, _, err := l.in.ReadRune()
-	if err != nil {
-		return r, err
-	}
-
-	if r == '\n' {
-		l.absRow++
-		l.absCol = 0
-	} else {
-		l.absCol++
-	}
-
-	return r, err
-}
-
-func (l *Lexer) peekRune() (rune, error) {
-	r, _, err := l.in.ReadRune()
-	if err != nil {
-		return r, err
-	}
-
-	if err := l.in.UnreadRune(); err != nil {
-		return r, err
-	}
-	return r, nil
-}
-
-func (l *Lexer) readAndPeek() (rune, rune, error) {
-	r, err := l.readRune()
-	if err != nil {
-		return r, 0, err
-	}
-
-	n, err := l.peekRune()
-	return r, n, err
-}
-
-func (l *Lexer) bufferRune(r rune) {
-	l.out.WriteRune(r)
-	if l.row < 0 && l.col < 0 {
-		l.row, l.col = l.absRow, l.absCol
-	}
-}
-
-// HasNext returns true if Next should be called, and false if it should not be
-// called and Err should be called instead. When HasNext returns false the Lexer
-// is considered to be done
-func (l *Lexer) HasNext() bool {
-	for {
-		if len(l.next) > 0 {
-			return true
-		} else if l.cur == nil {
-			return false
-		}
-		l.cur = l.cur(l)
-	}
-}
-
-// Next returns the next available token. HasNext must be called before every
-// call to Next
-func (l *Lexer) Next() Token {
-	t := l.next[0]
-	l.next = l.next[1:]
-	if len(l.next) == 0 {
-		l.next = nil
-	}
-	return t
-}
-
-////////////////////////////////////////////////////////////////////////////////
-// the actual fsm
-
-var whitespaceSet = " \n\r\t\v\f"
-var punctuationSet = ",>"
-var wrapperSet = "{}()"
-var identifierSepSet = whitespaceSet + punctuationSet + wrapperSet
-
-func lex(l *Lexer) lexerFn {
-	r, err := l.readRune()
-	if err != nil {
-		l.emitErr(err)
-		return nil
-	}
-
-	// handle comments first, cause we have to peek for those. We ignore errors,
-	// and assume that any error that would happen here will happen again the
-	// next read
-	if n, _ := l.peekRune(); r == '/' && n == '/' {
-		return lexLineComment
-	} else if r == '/' && n == '*' {
-		return lexBlockComment
-	}
-
-	return lexSingleRune(l, r)
-}
-
-func lexSingleRune(l *Lexer, r rune) lexerFn {
-	switch {
-	case strings.ContainsRune(whitespaceSet, r):
-		return lex
-	case strings.ContainsRune(punctuationSet, r):
-		l.bufferRune(r)
-		l.emit(Punctuation)
-		return lex
-	case strings.ContainsRune(wrapperSet, r):
-		l.bufferRune(r)
-		l.emit(Wrapper)
-		return lex
-	case r == '"' || r == '\'' || r == '`':
-		canEscape := r != '`'
-		return lexStrStart(l, r, makeLexStr(r, canEscape))
-	default:
-		l.bufferRune(r)
-		return lexIdentifier
-	}
-}
-
-func lexIdentifier(l *Lexer) lexerFn {
-	r, err := l.readRune()
-	if err != nil {
-		l.emit(Identifier)
-		l.emitErr(err)
-		return nil
-	}
-
-	if strings.ContainsRune(identifierSepSet, r) {
-		l.emit(Identifier)
-		return lexSingleRune(l, r)
-	}
-
-	l.bufferRune(r)
-
-	return lexIdentifier
-}
-
-func lexLineComment(l *Lexer) lexerFn {
-	r, err := l.readRune()
-	if err != nil {
-		l.emitErr(err)
-		return nil
-	}
-	if r == '\n' {
-		return lex
-	}
-	return lexLineComment
-}
-
-// assumes the starting / has been read already
-func lexBlockComment(l *Lexer) lexerFn {
-	depth := 1
-
-	var recurse lexerFn
-	recurse = func(l *Lexer) lexerFn {
-		r, err := l.readRune()
-		if err != nil {
-			l.emitErr(err)
-			return nil
-		}
-		n, _ := l.peekRune()
-
-		if r == '/' && n == '*' {
-			depth++
-		} else if r == '*' && n == '/' {
-			depth--
-		}
-
-		if depth == 0 {
-			return lexSkipThen(lex)
-		}
-		return recurse
-	}
-	return recurse
-}
-
-func lexStrStart(lexer *Lexer, r rune, then lexerFn) lexerFn {
-	lexer.bufferRune(r)
-	return then
-}
-
-func makeLexStr(quoteC rune, canEscape bool) lexerFn {
-	var fn lexerFn
-	fn = func(l *Lexer) lexerFn {
-		r, n, err := l.readAndPeek()
-		if err != nil {
-			if err == io.EOF {
-				if r == quoteC {
-					l.bufferRune(r)
-					l.emit(String)
-					l.emitErr(err)
-					return nil
-				}
-				l.emitErr(errors.New("expected end of string, got end of file"))
-				return nil
-			}
-		}
-
-		if canEscape && r == '\\' && n == quoteC {
-			l.bufferRune(r)
-			l.bufferRune(n)
-			return lexSkipThen(fn)
-		}
-
-		l.bufferRune(r)
-		if r == quoteC {
-			l.emit(String)
-			return lex
-		}
-
-		return fn
-	}
-	return fn
-}
-
-func lexSkipThen(then lexerFn) lexerFn {
-	return func(l *Lexer) lexerFn {
-		if _, err := l.readRune(); err != nil {
-			l.emitErr(err)
-			return nil
-		}
-		return then
-	}
-}

lexer/lexer_test.go

@@ -1,82 +0,0 @@
-package lexer
-
-import (
-	"bytes"
-	. "testing"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-var lexTestSrc = `
-	// this is a comment
-	// // this is also a comment
-	a
-	anIdentifier
-	1
-	100
-	1.5
-	1.5e9
-
-	/*
-		some stuff
-	*/
-
-	/* this should actually work */
-	/*/
-
-	/*
-		nested!
-		/*
-			wtf this is crazy
-		*/
-	*/
-
-	(punctuation,is{cool}> )
-	-tab
-
-	"this is a string", "and so is this one"
-	"\"foo"
-	"bar\"baz\""
-	"buz\0"
-`
-
-func TestLex(t *T) {
-	l := New(bytes.NewBufferString(lexTestSrc))
-
-	assertNext := func(typ TokenType, val string, row, col int) {
-		t.Logf("asserting %s %q [row:%d col:%d]", typ, val, row, col)
-		require.True(t, l.HasNext())
-		tok := l.Next()
-		assert.Equal(t, typ, tok.TokenType)
-		assert.Equal(t, val, tok.Val)
-		assert.Equal(t, row, tok.Row)
-		assert.Equal(t, col, tok.Col)
-	}
-
-	assertNext(Identifier, "a", 3, 2)
-	assertNext(Identifier, "anIdentifier", 4, 2)
-	assertNext(Identifier, "1", 5, 2)
-	assertNext(Identifier, "100", 6, 2)
-	assertNext(Identifier, "1.5", 7, 2)
-	assertNext(Identifier, "1.5e9", 8, 2)
-	assertNext(Wrapper, "(", 24, 2)
-	assertNext(Identifier, "punctuation", 24, 3)
-	assertNext(Punctuation, ",", 24, 14)
-	assertNext(Identifier, "is", 24, 15)
-	assertNext(Wrapper, "{", 24, 17)
-	assertNext(Identifier, "cool", 24, 18)
-	assertNext(Wrapper, "}", 24, 22)
-	assertNext(Punctuation, ">", 24, 23)
-	assertNext(Wrapper, ")", 24, 25)
-	assertNext(Identifier, "-tab", 25, 2)
-	assertNext(String, `"this is a string"`, 27, 2)
-	assertNext(Punctuation, ",", 27, 20)
-	assertNext(String, `"and so is this one"`, 27, 22)
-	assertNext(String, `"\"foo"`, 28, 2)
-	assertNext(String, `"bar\"baz\""`, 29, 2)
-	assertNext(String, `"buz\0"`, 30, 2)
-	assertNext(EOF, "EOF", 31, 0)
-
-	assert.False(t, l.HasNext())
-}

main.go

@@ -1,47 +0,0 @@
-package main
-
-import (
-	"fmt"
-
-	"github.com/mediocregopher/ginger/lang"
-	"github.com/mediocregopher/ginger/vm"
-)
-
-func main() {
-	mkcmd := func(a lang.Atom, args ...lang.Term) lang.Tuple {
-		if len(args) == 1 {
-			return lang.Tuple{a, args[0]}
-		}
-		return lang.Tuple{a, lang.Tuple(args)}
-	}
-	mkint := func(i string) lang.Tuple {
-		return lang.Tuple{vm.Int, lang.Const(i)}
-	}
-
-	//foo := lang.Atom("foo")
-	//tt := []lang.Term{
-	//	mkcmd(vm.Assign, foo, mkint("1")),
-	//	mkcmd(vm.Add, mkcmd(vm.Tuple, mkcmd(vm.Var, foo), mkint("2"))),
-	//}
-
-	foo := lang.Atom("foo")
-	bar := lang.Atom("bar")
-	baz := lang.Atom("baz")
-	tt := []lang.Term{
-		mkcmd(vm.Assign, foo, mkcmd(vm.Tuple, mkint("1"), mkint("2"))),
-		mkcmd(vm.Assign, bar, mkcmd(vm.Add, mkcmd(vm.Var, foo))),
-		mkcmd(vm.Assign, baz, mkcmd(vm.Add, mkcmd(vm.Var, foo))),
-		mkcmd(vm.Add, mkcmd(vm.Tuple, mkcmd(vm.Var, bar), mkcmd(vm.Var, baz))),
-	}
-
-	mod, err := vm.Build(tt...)
-	if err != nil {
-		panic(err)
-	}
-	defer mod.Dispose()
-
-	mod.Dump()
-
-	out, err := mod.Run()
-	fmt.Printf("\n\n########\nout: %v %v\n", out, err)
-}

sandbox/list/list.go

@@ -1,39 +0,0 @@
-package list
-
-import "fmt"
-
-/*
-	+ size isn't really _necessary_ unless O(1) Len is wanted
-	+ append doesn't work well on stack
-*/
-
-type List struct {
-	// in practice this would be a constant size, with the compiler knowing the
-	// size
-	underlying []int
-	head, size int
-}
-
-func New(ii ...int) List {
-	l := List{
-		underlying: make([]int, ii),
-		size:       len(ii),
-	}
-	copy(l.underlying, ii)
-	return l
-}
-
-func (l List) Len() int {
-	return l.size
-}
-
-func (l List) HeadTail() (int, List) {
-	if l.size == 0 {
-		panic(fmt.Sprintf("can't take HeadTail of empty list"))
-	}
-	return l.underlying[l.head], List{
-		underlying: l.underlying,
-		head:       l.head + 1,
-		size:       l.size - 1,
-	}
-}

sandbox/syntax.txt

@@ -0,0 +1,108 @@
+# 2021/08/26
+#
+# output of godoc on gg is this:
+
+var ZeroGraph = &Graph{ ... }
+func Equal(g1, g2 *Graph) bool
+type Edge struct{ ... }
+type Graph struct{ ... }
+type OpenEdge struct{ ... }
+    func TupleOut(ins []OpenEdge, edgeVal Value) OpenEdge
+    func ValueOut(val, edgeVal Value) OpenEdge
+type Value struct{ ... }
+    func NewValue(V interface{}) Value
+type Vertex struct{ ... }
+type VertexType string
+    const ValueVertex VertexType = "value" ...
+
+We just need to formulate a syntax which describes these operations and
+entities.
+
+Based on an old note I found in this file it seems like it reads
+better to actually order everything "backwards" in the syntax, so I'm going to
+go with that. I left the note at the bottom, commented out
+
+-(<openEdge>,...)           TupleOut                 (an openEdge)
+-<edgeVal>-(<openEdge>,...) TupleOut with an edgeVal (an openEdge)
+-<val>                      ValueOut                 (an openEdge)
+-<edgeVal>-<val>            ValueOut with an edgeVal (an openEdge)
+{<val> <openEdge>, ...}     ValueIn                  (a graph)
+
+values can only be alphanumeric, or graphs.
+TODO what to do about negative numbers? -1 is ambiguous
+
+This means the below fibonnaci can be done using:
+
+{
+    decr -{ out -sub-(-in, -1) }
+
+    out -{
+        n -0-in,
+        a -1-in,
+        b -2-in,
+
+        out -if-(
+            -zero?-n,
+            -a,
+            -recur-(
+                -decr-n,
+                -b,
+                -add-(-a,-b)
+            ),
+        )
+    }-(-in, -0, -1)
+}
+
+###
+
+Let's try to get rid of all the ugly prefix dashes (and maybe solve the -1
+question). We ditch the dashes all-together; TupleOut with an edgeVal can be
+done by just joining the two, and ValueOut with an edgeVal we can just make look
+like a TupleOut with a single openEdge (which... it kind of is anyway).
+
+(<openEdge>,...)          TupleOut                 (an openEdge)
+<edgeVal>(<openEdge>,...) TupleOut with an edgeVal (an openEdge)
+<val>                     ValueOut                 (an openEdge)
+<edgeVal>(<val>)          ValueOut with an edgeVal (an openEdge)
+{<val> <openEdge>[, ...]} ValueIn                  (a graph)
+
+values can only be alphanumeric, or graphs.
+
+```
+{
+    decr { out add(in, -1) }
+
+    out {
+        n 0(in),
+        a 1(in),
+        b 2(in),
+
+        out if(
+            zero?(n),
+            a,
+            recur(decr(n), b, add(a,b))
+        )
+
+    }(in, 0, 1)
+}
+```
+
+################
+# The Old Note #
+################
+#
+#decr- add- |- in
+#           |- (-1)
+#
+#fib- (
+#    fibInner- (
+#        {n, a, b}- in
+#        out- if- |- zero?- n
+#                 |- a
+#                 |- fibInner- |- decr- n
+#                              |- b
+#                              |- add- {a,b}
+#    )
+#)
+#
+#out- fib- atoi- first- in

vm/cmds.go

@@ -1,280 +0,0 @@
-package vm
-
-import (
-	"errors"
-	"fmt"
-	"strconv"
-
-	"github.com/mediocregopher/ginger/lang"
-	"llvm.org/llvm/bindings/go/llvm"
-)
-
-type op interface {
-	inType() valType
-	outType() valType
-	build(*Module) (llvm.Value, error)
-}
-
-type valType struct {
-	term lang.Term
-	llvm llvm.Type
-}
-
-func (vt valType) isInt() bool {
-	return lang.Equal(Int, vt.term)
-}
-
-func (vt valType) eq(vt2 valType) bool {
-	return lang.Equal(vt.term, vt2.term) && vt.llvm == vt2.llvm
-}
-
-// primitive valTypes
-var (
-	valTypeVoid = valType{term: lang.Tuple{}, llvm: llvm.VoidType()}
-	valTypeInt  = valType{term: Int, llvm: llvm.Int64Type()}
-)
-
-////////////////////////////////////////////////////////////////////////////////
-
-// most types don't have an input, so we use this as a shortcut
-type voidIn struct{}
-
-func (voidIn) inType() valType {
-	return valTypeVoid
-}
-
-////////////////////////////////////////////////////////////////////////////////
-
-type intOp struct {
-	voidIn
-	c lang.Const
-}
-
-func (io intOp) outType() valType {
-	return valTypeInt
-}
-
-func (io intOp) build(mod *Module) (llvm.Value, error) {
-	ci, err := strconv.ParseInt(string(io.c), 10, 64)
-	if err != nil {
-		return llvm.Value{}, err
-	}
-	return llvm.ConstInt(llvm.Int64Type(), uint64(ci), false), nil
-}
-
-////////////////////////////////////////////////////////////////////////////////
-
-type tupOp struct {
-	voidIn
-	els []op
-}
-
-func (to tupOp) outType() valType {
-	termTypes := make(lang.Tuple, len(to.els))
-	llvmTypes := make([]llvm.Type, len(to.els))
-	for i := range to.els {
-		elValType := to.els[i].outType()
-		termTypes[i] = elValType.term
-		llvmTypes[i] = elValType.llvm
-	}
-	vt := valType{term: lang.Tuple{Tuple, termTypes}}
-	if len(llvmTypes) == 0 {
-		vt.llvm = llvm.VoidType()
-	} else {
-		vt.llvm = llvm.StructType(llvmTypes, false)
-	}
-	return vt
-}
-
-func (to tupOp) build(mod *Module) (llvm.Value, error) {
-	str := llvm.Undef(to.outType().llvm)
-	var val llvm.Value
-	var err error
-	for i := range to.els {
-		if val, err = to.els[i].build(mod); err != nil {
-			return llvm.Value{}, err
-		}
-		str = mod.b.CreateInsertValue(str, val, i, "")
-	}
-	return str, err
-}
-
-////////////////////////////////////////////////////////////////////////////////
-
-type tupElOp struct {
-	voidIn
-	tup op
-	i   int
-}
-
-func (teo tupElOp) outType() valType {
-	tupType := teo.tup.outType()
-	return valType{
-		llvm: tupType.llvm.StructElementTypes()[teo.i],
-		term: tupType.term.(lang.Tuple)[1].(lang.Tuple)[1],
-	}
-}
-
-func (teo tupElOp) build(mod *Module) (llvm.Value, error) {
-	if to, ok := teo.tup.(tupOp); ok {
-		return to.els[teo.i].build(mod)
-	}
-
-	tv, err := teo.tup.build(mod)
-	if err != nil {
-		return llvm.Value{}, err
-	}
-	return mod.b.CreateExtractValue(tv, teo.i, ""), nil
-}
-
-////////////////////////////////////////////////////////////////////////////////
-
-type varOp struct {
-	op
-	v     llvm.Value
-	built bool
-}
-
-func (vo *varOp) build(mod *Module) (llvm.Value, error) {
-	if !vo.built {
-		var err error
-		if vo.v, err = vo.op.build(mod); err != nil {
-			return llvm.Value{}, err
-		}
-		vo.built = true
-	}
-	return vo.v, nil
-}
-
-type varCtx map[string]*varOp
-
-func (c varCtx) assign(name string, vo *varOp) error {
-	if _, ok := c[name]; ok {
-		return fmt.Errorf("var %q already assigned", name)
-	}
-	c[name] = vo
-	return nil
-}
-
-func (c varCtx) get(name string) (*varOp, error) {
-	if o, ok := c[name]; ok {
-		return o, nil
-	}
-	return nil, fmt.Errorf("var %q referenced before assignment", name)
-}
-
-////////////////////////////////////////////////////////////////////////////////
-
-type addOp struct {
-	voidIn
-	a, b op
-}
-
-func (ao addOp) outType() valType {
-	return ao.a.outType()
-}
-
-func (ao addOp) build(mod *Module) (llvm.Value, error) {
-	av, err := ao.a.build(mod)
-	if err != nil {
-		return llvm.Value{}, err
-	}
-	bv, err := ao.b.build(mod)
-	if err != nil {
-		return llvm.Value{}, err
-	}
-	return mod.b.CreateAdd(av, bv, ""), nil
-}
-
-////////////////////////////////////////////////////////////////////////////////
-
-func termToOp(ctx varCtx, t lang.Term) (op, error) {
-	aPat := func(a lang.Atom) lang.Tuple {
-		return lang.Tuple{lang.AAtom, a}
-	}
-	cPat := func(t lang.Term) lang.Tuple {
-		return lang.Tuple{lang.AConst, t}
-	}
-	tPat := func(el ...lang.Term) lang.Tuple {
-		return lang.Tuple{Tuple, lang.Tuple(el)}
-	}
-
-	if !lang.Match(tPat(aPat(lang.AUnder), lang.TDblUnder), t) {
-		return nil, fmt.Errorf("term %v does not look like a vm command", t)
-	}
-	k := t.(lang.Tuple)[0].(lang.Atom)
-	v := t.(lang.Tuple)[1]
-
-	// for when v is a Tuple argument, convenience function for casting
-	vAsTup := func(n int) ([]op, error) {
-		vop, err := termToOp(ctx, v)
-		if err != nil {
-			return nil, err
-		}
-		ops := make([]op, n)
-		for i := range ops {
-			ops[i] = tupElOp{tup: vop, i: i}
-		}
-
-		return ops, nil
-	}
-
-	switch k {
-	case Int:
-		if !lang.Match(cPat(lang.AUnder), v) {
-			return nil, errors.New("int requires constant arg")
-		}
-		return intOp{c: v.(lang.Const)}, nil
-	case Tuple:
-		if !lang.Match(lang.Tuple{Tuple, lang.AUnder}, v) {
-			return nil, errors.New("tup requires tuple arg")
-		}
-		tup := v.(lang.Tuple)
-		tc := tupOp{els: make([]op, len(tup))}
-		var err error
-		for i := range tup {
-			if tc.els[i], err = termToOp(ctx, tup[i]); err != nil {
-				return nil, err
-			}
-		}
-		return tc, nil
-	case Var:
-		if !lang.Match(aPat(lang.AUnder), v) {
-			return nil, errors.New("var requires atom arg")
-		}
-		name := v.(lang.Atom).String()
-		return ctx.get(name)
-
-	case Assign:
-		if !lang.Match(tPat(tPat(aPat(Var), aPat(lang.AUnder)), lang.TDblUnder), v) {
-			return nil, errors.New("assign requires 2-tuple arg, the first being a var")
-		}
-		tup := v.(lang.Tuple)
-		name := tup[0].(lang.Tuple)[1].String()
-		o, err := termToOp(ctx, tup[1])
-		if err != nil {
-			return nil, err
-		}
-
-		vo := &varOp{op: o}
-		if err := ctx.assign(name, vo); err != nil {
-			return nil, err
-		}
-		return vo, nil
-
-	// Add is special in some way, I think it's a function not a compiler op,
-	// not sure yet though
-	case Add:
-		els, err := vAsTup(2)
-		if err != nil {
-			return nil, err
-		} else if !els[0].outType().eq(valTypeInt) {
-			return nil, errors.New("add args must be numbers of the same type")
-		} else if !els[1].outType().eq(valTypeInt) {
-			return nil, errors.New("add args must be numbers of the same type")
-		}
-		return addOp{a: els[0], b: els[1]}, nil
-	default:
-		return nil, fmt.Errorf("op %v unknown, or its args are malformed", t)
-	}
-}

vm/function.go

@@ -0,0 +1,246 @@
+package vm
+
+import (
+	"errors"
+	"fmt"
+
+	"code.betamike.com/mediocregopher/ginger/gg"
+	"code.betamike.com/mediocregopher/ginger/graph"
+)
+
+// Function is an entity which accepts an argument Value and performs some
+// internal processing on that argument to return a resultant Value.
+type Function interface {
+	Perform(Value) Value
+}
+
+// FunctionFunc is a function which implements the Function interface.
+type FunctionFunc func(Value) Value
+
+// Perform calls the underlying FunctionFunc directly.
+func (f FunctionFunc) Perform(arg Value) Value {
+	return f(arg)
+}
+
+// Identity returns an Function which always returns the given Value,
+// regardless of the input argument.
+//
+// TODO this might not be the right name
+func Identity(val Value) Function {
+	return FunctionFunc(func(Value) Value {
+		return val
+	})
+}
+
+var (
+	valNameIn     = Value{Value: gg.Name("!in")}
+	valNameOut    = Value{Value: gg.Name("!out")}
+	valNameIf     = Value{Value: gg.Name("!if")}
+	valNameRecur  = Value{Value: gg.Name("!recur")}
+	valNumberZero = Value{Value: gg.Number(0)}
+)
+
+func checkGraphForFunction(g *gg.Graph) error {
+	for _, val := range g.AllValueIns() {
+		if val.Name == nil {
+			return fmt.Errorf("non-name %v cannot have incoming edges", val)
+		}
+
+		if !(Value{Value: val}).Equal(valNameOut) && (*val.Name)[0] == '!' {
+			return fmt.Errorf("name %v cannot start with a '!'", val)
+		}
+	}
+
+	// TODO check for acyclic-ness
+
+	return nil
+}
+
+// FunctionFromGraph wraps the given Graph such that it can be used as an
+// Function. The given Scope determines what values outside of the Graph are
+// available for use within the Function.
+func FunctionFromGraph(g *gg.Graph, scope Scope) (Function, error) {
+
+	if err := checkGraphForFunction(g); err != nil {
+		return nil, err
+	}
+
+	// edgeFn is distinct from a generic Function in that the Value passed into
+	// Perform will _always_ be the value of "in" for the overall Function.
+	//
+	// edgeFns will wrap each other, passing "in" downwards to the leaf edgeFns.
+	type edgeFn Function
+
+	var compileEdge func(*gg.OpenEdge) (edgeFn, error)
+
+	// TODO memoize?
+	valToEdgeFn := func(val Value) (edgeFn, error) {
+
+		if val.Name == nil {
+			return edgeFn(Identity(val)), nil
+		}
+
+		if val.Equal(valNameIn) {
+			return edgeFn(FunctionFunc(func(inArg Value) Value {
+				return inArg
+			})), nil
+		}
+
+		edgesIn := g.ValueIns(val.Value)
+
+		name := *val.Name
+
+		if l := len(edgesIn); l == 0 {
+			resolvedVal, err := scope.Resolve(name)
+			if errors.Is(err, ErrNameNotDefined) {
+				return edgeFn(Identity(val)), nil
+			} else if err != nil {
+				return nil, fmt.Errorf("resolving name %q from the outer scope: %w", name, err)
+			}
+
+			return edgeFn(Identity(resolvedVal)), nil
+
+		} else if l != 1 {
+			return nil, fmt.Errorf("resolved name %q to %d input edges, rather than one", name, l)
+		}
+
+		edge := edgesIn[0]
+
+		return compileEdge(edge)
+	}
+
+	// "out" resolves to more than a static value, treat the graph as a full
+	// operation.
+
+	// thisFn is used to support recur. It will get filled in with the Function
+	// which is returned by this function, once that Function is created.
+	thisFn := new(Function)
+
+	compileEdge = func(edge *gg.OpenEdge) (edgeFn, error) {
+
+		return graph.MapReduce[gg.OptionalValue, gg.Value, edgeFn](
+			edge,
+			func(ggVal gg.Value) (edgeFn, error) {
+				return valToEdgeFn(Value{Value: ggVal})
+			},
+			func(ggEdgeVal gg.OptionalValue, inEdgeFns []edgeFn) (edgeFn, error) {
+				if ggEdgeVal.Equal(valNameIf.Value) {
+
+					if len(inEdgeFns) != 3 {
+						return nil, fmt.Errorf("'!if' requires a 3-tuple argument")
+					}
+
+					return edgeFn(FunctionFunc(func(inArg Value) Value {
+
+						if pred := inEdgeFns[0].Perform(inArg); pred.Equal(valNumberZero) {
+							return inEdgeFns[2].Perform(inArg)
+						}
+
+						return inEdgeFns[1].Perform(inArg)
+
+					})), nil
+				}
+
+				// "!if" statements (above) are the only case where we want the
+				// input edges to remain separated, otherwise they should always
+				// be combined into a single edge whose value is a tuple. Do
+				// that here.
+
+				inEdgeFn := inEdgeFns[0]
+
+				if len(inEdgeFns) > 1 {
+					inEdgeFn = edgeFn(FunctionFunc(func(inArg Value) Value {
+						tupVals := make([]Value, len(inEdgeFns))
+
+						for i := range inEdgeFns {
+							tupVals[i] = inEdgeFns[i].Perform(inArg)
+						}
+
+						return Tuple(tupVals...)
+					}))
+				}
+
+				var edgeVal Value
+				if ggEdgeVal.Valid {
+					edgeVal.Value = ggEdgeVal.Value
+				}
+
+				if edgeVal.IsZero() {
+					return inEdgeFn, nil
+				}
+
+				if edgeVal.Equal(valNameRecur) {
+					return edgeFn(FunctionFunc(func(inArg Value) Value {
+						return (*thisFn).Perform(inEdgeFn.Perform(inArg))
+					})), nil
+				}
+
+				if edgeVal.Graph != nil {
+
+					opFromGraph, err := FunctionFromGraph(edgeVal.Graph, scope)
+					if err != nil {
+						return nil, fmt.Errorf("compiling graph to operation: %w", err)
+					}
+
+					edgeVal = Value{Function: opFromGraph}
+				}
+
+				// The Function is known at compile-time, so we can wrap it
+				// directly into an edgeVal using the existing inEdgeFn as the
+				// input.
+				if edgeVal.Function != nil {
+					return edgeFn(FunctionFunc(func(inArg Value) Value {
+						return edgeVal.Function.Perform(inEdgeFn.Perform(inArg))
+					})), nil
+				}
+
+				// the edgeVal is not a Function at compile time, and so
+				// it must become one at runtime. We must resolve edgeVal to an
+				// edgeFn as well (edgeEdgeFn), and then at runtime that is
+				// given the inArg and (hopefully) the resultant Function is
+				// called.
+
+				edgeEdgeFn, err := valToEdgeFn(edgeVal)
+
+				if err != nil {
+					return nil, err
+				}
+
+				return edgeFn(FunctionFunc(func(inArg Value) Value {
+
+					runtimeEdgeVal := edgeEdgeFn.Perform(inArg)
+
+					if runtimeEdgeVal.Graph != nil {
+
+						runtimeFn, err := FunctionFromGraph(
+							runtimeEdgeVal.Graph, scope,
+						)
+
+						if err != nil {
+							panic(fmt.Sprintf("compiling graph to operation: %v", err))
+						}
+
+						runtimeEdgeVal = Value{Function: runtimeFn}
+					}
+
+					if runtimeEdgeVal.Function == nil {
+						panic("edge value must be an operation")
+					}
+
+					return runtimeEdgeVal.Function.Perform(inEdgeFn.Perform(inArg))
+
+				})), nil
+			},
+		)
+	}
+
+	graphFn, err := valToEdgeFn(valNameOut)
+
+	if err != nil {
+		return nil, err
+	}
+
+	*thisFn = Function(graphFn)
+
+	return Function(graphFn), nil
+}

vm/scope.go

@@ -0,0 +1,58 @@
+package vm
+
+import (
+	"errors"
+)
+
+// ErrNameNotDefined is returned from Scope.Resolve when a name could not be
+// resolved within a Scope.
+var ErrNameNotDefined = errors.New("not defined")
+
+// Scope encapsulates a set of name->Value mappings.
+type Scope interface {
+
+	// Resolve accepts a name and returns an Value, or returns
+	// ErrNameNotDefined.
+	Resolve(string) (Value, error)
+}
+
+// ScopeMap implements the Scope interface.
+type ScopeMap map[string]Value
+
+var _ Scope = ScopeMap{}
+
+// Resolve uses the given name as a key into the ScopeMap map, and
+// returns the Operation held there for the key, if any.
+func (m ScopeMap) Resolve(name string) (Value, error) {
+
+	v, ok := m[name]
+
+	if !ok {
+		return Value{}, ErrNameNotDefined
+	}
+
+	return v, nil
+}
+
+type scopeWith struct {
+	Scope // parent
+	name  string
+	val   Value
+}
+
+// ScopeWith returns a copy of the given Scope, except that evaluating the given
+// name will always return the given Value.
+func ScopeWith(scope Scope, name string, val Value) Scope {
+	return &scopeWith{
+		Scope: scope,
+		name:  name,
+		val:   val,
+	}
+}
+
+func (s *scopeWith) Resolve(name string) (Value, error) {
+	if name == s.name {
+		return s.val, nil
+	}
+	return s.Scope.Resolve(name)
+}

vm/scope_global.go

@@ -0,0 +1,61 @@
+package vm
+
+import (
+	"fmt"
+
+	"code.betamike.com/mediocregopher/ginger/gg"
+)
+
+func globalFn(fn func(Value) (Value, error)) Value {
+	return Value{
+		Function: FunctionFunc(func(in Value) Value {
+			res, err := fn(in)
+			if err != nil {
+				panic(err)
+			}
+			return res
+		}),
+	}
+}
+
+// GlobalScope contains operations and values which are available from within
+// any operation in a ginger program.
+var GlobalScope = ScopeMap{
+
+	"!add": globalFn(func(val Value) (Value, error) {
+
+		var sum int64
+
+		for _, tupVal := range val.Tuple {
+
+			if tupVal.Number == nil {
+				return Value{}, fmt.Errorf("add requires a non-zero tuple of numbers as an argument")
+			}
+
+			sum += *tupVal.Number
+		}
+
+		return Value{Value: gg.Value{Number: &sum}}, nil
+
+	}),
+
+	"!tupEl": globalFn(func(val Value) (Value, error) {
+
+		tup, i := val.Tuple[0], val.Tuple[1]
+
+		return tup.Tuple[int(*i.Number)], nil
+
+	}),
+
+	"!isZero": globalFn(func(val Value) (Value, error) {
+
+		if *val.Number == 0 {
+			one := int64(1)
+			return Value{Value: gg.Value{Number: &one}}, nil
+		}
+
+		zero := int64(0)
+		return Value{Value: gg.Value{Number: &zero}}, nil
+
+	}),
+}

vm/vm.go

@@ -1,129 +1,123 @@
+// Package vm implements the execution of gg.Graphs as programs.
 package vm
 
 import (
 	"errors"
 	"fmt"
-	"sync"
+	"io"
+	"strings"
 
-	"github.com/mediocregopher/ginger/lang"
-
-	"llvm.org/llvm/bindings/go/llvm"
+	"code.betamike.com/mediocregopher/ginger/gg"
+	"code.betamike.com/mediocregopher/ginger/graph"
 )
 
-// Types supported by the vm in addition to those which are part of lang
-var (
-	Atom  = lang.AAtom
-	Tuple = lang.ATuple
-	Int   = lang.Atom("int")
-)
+// ZeroValue is a Value with no fields set. It is equivalent to the 0-tuple.
+var ZeroValue Value
 
-// Ops supported by the vm
-var (
-	Add    = lang.Atom("add")
-	Assign = lang.Atom("assign")
-	Var    = lang.Atom("var")
-)
+// Value extends a gg.Value to include Functions and Tuples as a possible
+// types.
+type Value struct {
+	gg.Value
 
-////////////////////////////////////////////////////////////////////////////////
-
-// Module contains a compiled set of code which can be run, dumped in IR form,
-// or compiled. A Module should be Dispose()'d of once it's no longer being
-// used.
-type Module struct {
-	b      llvm.Builder
-	m      llvm.Module
-	ctx    varCtx
-	mainFn llvm.Value
+	Function
+	Tuple []Value
 }
 
-var initOnce sync.Once
-
-// Build creates a new Module by compiling the given Terms as code
-// TODO only take in a single Term, implement List and use that with a do op
-func Build(tt ...lang.Term) (*Module, error) {
-	initOnce.Do(func() {
-		llvm.LinkInMCJIT()
-		llvm.InitializeNativeTarget()
-		llvm.InitializeNativeAsmPrinter()
-	})
-	mod := &Module{
-		b:   llvm.NewBuilder(),
-		m:   llvm.NewModule(""),
-		ctx: varCtx{},
-	}
-
-	var err error
-	if mod.mainFn, err = mod.buildFn(tt...); err != nil {
-		mod.Dispose()
-		return nil, err
-	}
-
-	if err := llvm.VerifyModule(mod.m, llvm.ReturnStatusAction); err != nil {
-		mod.Dispose()
-		return nil, fmt.Errorf("could not verify module: %s", err)
-	}
-
-	return mod, nil
+// Tuple returns a tuple Value comprising the given Values. Calling Tuple with
+// no arguments returns ZeroValue.
+func Tuple(vals ...Value) Value {
+	return Value{Tuple: vals}
 }
 
-// Dispose cleans up all resources held by the Module
-func (mod *Module) Dispose() {
-	// TODO this panics for some reason...
-	//mod.m.Dispose()
-	//mod.b.Dispose()
+// IsZero returns true if the Value is the zero value (aka the 0-tuple).
+// LexerToken (within the gg.Value) is ignored for this check.
+func (v Value) IsZero() bool {
+	return v.Equal(ZeroValue)
 }
 
-// TODO make this return a val once we get function types
-func (mod *Module) buildFn(tt ...lang.Term) (llvm.Value, error) {
-	if len(tt) == 0 {
-		return llvm.Value{}, errors.New("function cannot be empty")
-	}
+// Equal returns true if the passed in Value is equivalent, ignoring the
+// LexerToken on either Value.
+//
+// Will panic if the passed in v2 is not a Value from this package.
+func (v Value) Equal(v2g graph.Value) bool {
 
-	ops := make([]op, len(tt))
-	var err error
-	for i := range tt {
-		if ops[i], err = termToOp(mod.ctx, tt[i]); err != nil {
-			return llvm.Value{}, err
+	v2 := v2g.(Value)
+
+	switch {
+
+	case (v.Value != (gg.Value{}) || v2.Value != (gg.Value{})):
+		return v.Value.Equal(v2.Value)
+
+	case v.Function != nil || v2.Function != nil:
+		// for now we say that Functions can't be compared. This will probably
+		// get revisted later.
+		return false
+
+	case len(v.Tuple) == len(v2.Tuple):
+
+		for i := range v.Tuple {
+			if !v.Tuple[i].Equal(v2.Tuple[i]) {
+				return false
+			}
 		}
+
+		return true
+
+	default:
+
+		// if both were the zero value then both tuples would have the same
+		// length (0), which is covered by the previous check. So anything left
+		// over must be tuples with differing lengths.
+		return false
 	}
 
-	var llvmIns []llvm.Type
-	if in := ops[0].inType(); in.llvm.TypeKind() == llvm.VoidTypeKind {
-		llvmIns = []llvm.Type{}
-	} else {
-		llvmIns = []llvm.Type{in.llvm}
-	}
-	llvmOut := ops[len(ops)-1].outType().llvm
+}
 
-	fn := llvm.AddFunction(mod.m, "", llvm.FunctionType(llvmOut, llvmIns, false))
-	block := llvm.AddBasicBlock(fn, "")
-	mod.b.SetInsertPoint(block, block.FirstInstruction())
+func (v Value) String() string {
 
-	var out llvm.Value
-	for i := range ops {
-		if out, err = ops[i].build(mod); err != nil {
-			return llvm.Value{}, err
+	switch {
+
+	case v.Function != nil:
+
+		// We can try to get better strings for ops later
+		return "<fn>"
+
+	case v.Value != (gg.Value{}):
+		return v.Value.String()
+
+	default:
+
+		// we consider zero value to be the 0-tuple
+
+		strs := make([]string, len(v.Tuple))
+
+		for i := range v.Tuple {
+			strs[i] = v.Tuple[i].String()
 		}
+
+		return fmt.Sprintf("(%s)", strings.Join(strs, ", "))
+
 	}
-	mod.b.CreateRet(out)
-	return fn, nil
+
 }
 
-// Dump dumps the Module's IR to stdout
-func (mod *Module) Dump() {
-	mod.m.Dump()
-}
-
-// Run executes the Module
-// TODO input and output?
-func (mod *Module) Run() (interface{}, error) {
-	engine, err := llvm.NewExecutionEngine(mod.m)
+// EvaluateSource reads and parses the io.Reader as an operation, input is used
+// as the argument to the operation, and the resultant value is returned.
+//
+// scope contains pre-defined operations and values which are available during
+// the evaluation.
+func EvaluateSource(opSrc io.Reader, input Value, scope Scope) (Value, error) {
+	v, err := gg.NewDecoder(opSrc).Next()
 	if err != nil {
-		return nil, err
+		return Value{}, err
+	} else if v.Value.Graph == nil {
+		return Value{}, errors.New("value must be a graph")
 	}
-	defer engine.Dispose()
 
-	funcResult := engine.RunFunction(mod.mainFn, []llvm.GenericValue{})
-	defer funcResult.Dispose()
-	return funcResult.Int(false), nil
+	fn, err := FunctionFromGraph(v.Value.Graph, scope)
+	if err != nil {
+		return Value{}, err
+	}
+
+	return fn.Perform(input), nil
 }

vm/vm_test.go

@@ -1,84 +1,58 @@
 package vm
 
 import (
-	. "testing"
+	"bytes"
+	"strconv"
+	"testing"
 
-	"github.com/mediocregopher/ginger/lang"
+	"code.betamike.com/mediocregopher/ginger/gg"
+	"github.com/stretchr/testify/assert"
 )
 
-func TestCompiler(t *T) {
-	mkcmd := func(a lang.Atom, args ...lang.Term) lang.Tuple {
-		// TODO a 1-tuple should be the same as its element?
-		if len(args) == 1 {
-			return lang.Tuple{a, args[0]}
-		}
-		return lang.Tuple{a, lang.Tuple(args)}
-	}
-	mkint := func(i string) lang.Tuple {
-		return lang.Tuple{Int, lang.Const(i)}
-	}
-
-	type test struct {
-		in  []lang.Term
-		exp uint64
-	}
-
-	one := mkint("1")
-	two := mkint("2")
-	foo := mkcmd(Var, lang.Atom("foo"))
-	bar := mkcmd(Var, lang.Atom("bar"))
-	baz := mkcmd(Var, lang.Atom("baz"))
-
-	tests := []test{
+func TestVM(t *testing.T) {
+	tests := []struct {
+		src    string
+		in     Value
+		exp    Value
+		expErr string
+	}{
 		{
-			in:  []lang.Term{one},
-			exp: 1,
+			src: `{
+				incr = { !out = !add < (1, !in); };
+				!out = incr < incr < !in;
+			}`,
+			in:  Value{Value: gg.Number(5)},
+			exp: Value{Value: gg.Number(7)},
 		},
 		{
-			in: []lang.Term{
-				mkcmd(Add, mkcmd(Tuple, one, two)),
-			},
-			exp: 3,
+			src: `{
+				!foo = in;
+				!out = !foo;
+			}`,
+			in:     Value{Value: gg.Number(1)},
+			expErr: "name !foo cannot start with a '!'",
 		},
 		{
-			in: []lang.Term{
-				mkcmd(Assign, foo, one),
-				mkcmd(Add, mkcmd(Tuple, foo, two)),
-			},
-			exp: 3,
-		},
-		{
-			in: []lang.Term{
-				mkcmd(Assign, foo, mkcmd(Tuple, one, two)),
-				mkcmd(Add, foo),
-			},
-			exp: 3,
-		},
-		{
-			in: []lang.Term{
-				mkcmd(Assign, foo, mkcmd(Tuple, one, two)),
-				mkcmd(Assign, bar, mkcmd(Add, foo)),
-				mkcmd(Assign, baz, mkcmd(Add, foo)),
-				mkcmd(Add, mkcmd(Tuple, bar, baz)),
-			},
-			exp: 6,
+			src: `{foo = bar; !out = foo;}`,
+			in:  Value{},
+			exp: Value{Value: gg.Name("bar")},
 		},
 	}
 
-	for _, test := range tests {
-		t.Logf("testing program: %v", test.in)
-		mod, err := Build(test.in...)
-		if err != nil {
-			t.Fatalf("building failed: %s", err)
-		}
+	for i, test := range tests {
+		t.Run(strconv.Itoa(i), func(t *testing.T) {
+			t.Log(test.src)
+			val, err := EvaluateSource(
+				bytes.NewBufferString(test.src), test.in, GlobalScope,
+			)
 
-		out, err := mod.Run()
-		if err != nil {
-			mod.Dump()
-			t.Fatalf("running failed: %s", err)
-		} else if out != test.exp {
-			mod.Dump()
-			t.Fatalf("expected result %T:%v, got %T:%v", test.exp, test.exp, out, out)
-		}
+			if test.expErr != "" {
+				assert.Error(t, err)
+				assert.Equal(t, test.expErr, err.Error())
+			} else {
+				assert.NoError(t, err)
+				assert.True(t, val.Equal(test.exp), "%v != %v", test.exp, val)
+			}
+		})
 	}
 }