ginger names

static/src/_posts/2022-01-21-ginger-names.md

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+---
+title: >-
+    Ginger Names
+description: >-
+    Thoughts about a fundamental data type.
+tags: tech
+series: ginger
+---
+
+The ginger language has, so far, 2 core types implemented: numbers and names.
+Obviously there will be more coming later, but at this stage of development
+these are all that's really needed. Numbers are pretty self explanatory, but
+it's worth talking about names a bit.
+
+As they are currently defined, a name's only property is that it can either be
+equal or not equal to another name. Syntactically they are encoded as being any
+alphanumeric token starting with an alphabetic character. We might _think_ of
+them as being strings, but names lack nearly all capabilities that strings have:
+they cannot be iterated over, they cannot be concatenated, they cannot be split.
+Names can only be compared for equality.
+
+## Utility
+
+The use-case for names is self-explanatory: they are words which identify
+something from amongst a group.
+
+Consider your own name. It _might_ have an ostensible meaning. Mine, Brian,
+means "high" (as in... like a hill, which is the possible root word). But when
+people yell "Brian" across the room I'm in, they don't mean a hill. They mean
+me, because that word is used to identify me from amongst others. The etymology
+is essentially background information which doesn't matter.
+
+We use names all the time in programming, though we don't always call them that.
+Variable names, package names, type names, function names, struct field names.
+There's also keys which get used in hash maps, which are essentially names, as
+well as enumerations. By defining name as a core type we can cover a lot of
+ground.
+
+## Precedence
+
+This is not the first time a name has been used as a core type. Ruby has
+symbols, which look like `:this`. Clojure has keywords, which also look like
+`:this`, and it has symbols, which look like `this`. Erlang has atoms, which
+don't have a prefix and so look like `this`. I can't imagine these are the only
+examples. They are all called different things, but they're all essentially the
+same thing: a runtime value which can only be compared for equality.
+
+I can't speak much about ruby, but I _can_ speak about clojure and erlang.
+
+Clojure is a LISP language, meaning the language itself is described using the
+data types and structures built into the language. Ginger is also a LISP, though
+it uses graphs instead of lists.
+
+Clojure keywords are generally used as keys to hash maps, sentinel values, and
+enumerations. Besides keywords, clojure also makes use of symbols, which are
+used for variable and library names. There seems to be some kind of split
+ability on symbols, as they are expected to be separated on their periods when
+importing, as in `clojure.java.io`. There's also a quoting mechanism in clojure,
+where prefixing a symbol, or other value, with a single quote, like `'this`,
+prevents it from being evaluated as a variable or function call.
+
+It's also possible to have something get quoted multiple layers deep, like
+`'''this`. This can get confusing.
+
+Erlang is not a LISP language, but it does have atoms. These values are used in
+the same way that clojure keywords are used. There is no need for a
+corresponding symbol type like clojure has, since erlang is not a LISP and has
+no real macro system. Atoms are sort of used like symbols, in that functions and
+packages are identified by an atom, and so one can "call" an atom, like
+`this()`, in order to evaluate it.
+
+## Just Names
+
+I don't really see the need for clojure's separation between keywords and
+symbols. Symbols still need to be quoted in order to prevent evaluation either
+way, so you end up with three different entities to juggle (keywords, symbols,
+and symbols which won't be evaluated). Erlang's solution is simpler, atoms are
+just atoms, and since evaluation is explicit there's no need for quoting. Ginger
+names are like erlang atoms in that they are the only tool at hand.
+
+The approaches of erlang vs clojure could be reframed as explicit vs implicit
+evaluation of operations calls.
+
+In ginger evaluation is currently done implicitly, but in only two cases:
+
+* A value on an edge is evaluated to the first value which is a graph (which
+  then gets interpreted as an operation).
+
+* A leaf vertex with a name value is evaluated to the first value which is not a
+  name.
+
+In all other cases, the value is left as-is. A graph does not need to be quoted,
+since the need to evaluate a graph as an operation is already based on its
+placement as an edge or not. So the only case left where quoting is needed (if
+implicit evaluation continues to be used) is a name on a leaf vertex, as in the
+example before.
+
+As an example to explore explicit vs implicit quoting in ginger, if we want to
+programatically call the `AddValueIn` method on a graph, which terminates an
+open edge into a value, and that value is a name, it might look like this with
+implicit evaluation (the clojure-like example):
+
+```
+out = addValueIn < (g (quote < someName;) someValue; );
+
+* or, to borrow the clojure syntax, where single quote is a shortcut:
+
+out = addValueIn < (g; 'someName; someValue; );
+```
+
+In an explicit evaluation language, which ginger so far has not been and so this
+will look weird, we might end up with something like this:
+
+```
+out = addValueIn < (eval < g; someName; eval < someValue; );
+
+* with $ as sugar for the `eval`, like ' is a shortcut for `quote` in clojure:`
+
+out = addValueIn < ($g; someName; $someValue; );
+```
+
+I don't _like_ either pattern, and since it's such a specific case I feel like
+something less obtrusive could come up. So no decisions here yet.
+
+## Uniqueness
+
+There's another idea I haven't really gotten to the bottom of yet. The idea is
+that a name, _maybe_, shouldn't be considered equal to the same name unless they
+belong to the same graph.
+
+For example:
+
+```
+otherFoo = { out = 'foo } < ();
+
+out = equal < ('foo;  otherFoo; );
+```
+
+This would output false. `otherFoo`'s value is the name `foo`, and the value
+it's being compared to is also a name `foo`, but they are from different graphs
+and so are not equal. In essence, names are automatically namespaces.
+
+This idea only really makes sense in the context of packages, where a user
+(a developer) wants to import functionality from somewhere else and use it
+in their program. The code package which is imported will likely use name
+values internally to implement its functionality, but it shouldn't need to worry
+about naming conflicts with values passed in by the user. While it's possible to
+avoid conflicts if a package is designed conscientiously, it's also easy to mess
+up if one isn't careful. This becomes especially true when combining
+functionality of packages with overlapping functionality, where the data
+returned from one might looks _similar_ to that used by the other, but it's not
+necessarily true.
+
+On the other hand, this could create some real headaches for the developer, as
+they chase down errors which are caused because one `foo` isn't actually the
+same as another `foo`.
+
+What it really comes down to is the mechanism which packages use to function as
+packages. Forced namespaces will require packages to export all names which they
+expect the user to need to work with the package. So the ergonomics of that
+exporting, both on the user's and package's side, are really important in order
+to make this bearable.
+
+So it's hard to make any progress on determining if this idea is gonna work
+until the details of packaging are worked out. But for this idea to work the
+packaging is going to need to be designed with it in mind. It's a bit of a
+puzzle, and one that I'm going to marinate on longer, in addition to the quoting
+of names.
+
+And that's names, their current behavior and possible future behavior. Keep an
+eye out for more ginger posts in.... many months, because I'm going to go work
+on other things for a while (I say, with a post from a month ago having ended
+with the same sentiment).