ginger names
This commit is contained in:
Brian Picciano
parent
fdd02aff26
commit
bfcdeb6233
173
static/src/_posts/2022-01-21-ginger-names.md
Normal file
173
static/src/_posts/2022-01-21-ginger-names.md
Normal file
@ -0,0 +1,173 @@
|
||||
---
|
||||
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).
|
||||
Loading…
Reference in New Issue
Block a user