Functions should properly close over bindings #16

New Issue

scott · 2024-12-09T23:04:16Z

scott commented

2024-12-09 23:04:16 +00:00

Currently, this gives a panic, unbound name foo.

let baz = {
  let foo = :foo
  fn bar () -> foo
}
baz ()

Should output :foo. Currently, I'm pretty sure this is because functions aren't capturing their context properly when evaluating the fn ast node (and not when they're actually run).

Currently, this gives a panic, `unbound name foo`. ``` let baz = { let foo = :foo fn bar () -> foo } baz () ``` Should output `:foo`. Currently, I'm pretty sure this is because functions aren't capturing their context properly when evaluating the `fn` ast node (and not when they're actually run).

scott added the

feature

core

labels 2024-12-09 23:04:26 +00:00

scott commented

2024-12-09 23:15:22 +00:00

This is what's causing the unbound name base errors now that I'm working on importing Prelude in #13 (comment).

The proper way to do this is to do a validation/compile pass, and in that, enumerate the bindings the function closes over, and then, instead of cloning the whole locals stack, create a new locals stack that only includes those bindings that are closed over.

That will also mean that a function actually should own a context? The lifetimes are going to be wild there, but let's give it a shot.

(That also means that, thankfully, generating stack traces should be pretty straightforward?)

This is what's causing the `unbound name base` errors now that I'm working on importing Prelude in https://alea.ludus.dev/scott/rudus/issues/13#issuecomment-1891. The proper way to do this is to do a validation/compile pass, and in that, enumerate the bindings the function closes over, and then, instead of cloning the whole locals stack, create a new locals stack that only includes those bindings that are closed over. That will also mean that a function actually should own a context? The lifetimes are going to be wild there, but let's give it a shot. (That also means that, thankfully, generating stack traces should be pretty straightforward?)

scott commented

2024-12-11 05:31:34 +00:00

With the work I've done today, circa 35e9d0373d, we have the validator properly identifying the values a function closes over, stuffing them into a hash table with the pointer to the Ast node as the key, and a HashSet containing the bindings that are closed over.

What's left to do is to rework the Fn branch of context::Context::eval to become its own Context-like thing that can be .evaled.

With the work I've done today, circa https://alea.ludus.dev/scott/rudus/commit/35e9d0373d7121b31cc3b8ab1f1c73b4cf4a61e3, we have the validator properly identifying the values a function closes over, stuffing them into a hash table with the pointer to the Ast node as the key, and a HashSet containing the bindings that are closed over. What's left to do is to rework the `Fn` branch of `context::Context::eval` to become its own `Context`-like thing that can be `.eval`ed.

scott added a new dependency 2024-12-11 05:32:22 +00:00

#13 Bring Prelude into Rust

scott added this to the Minimal replacement for Janet-based Ludus milestone 2024-12-11 05:36:14 +00:00

scott commented

2024-12-12 00:18:29 +00:00

This is working fine in a Ludus script, as of 6a01089973. Pulling from a simplified Prelude also works.

There's some weirdness, though, in Prelude. I don't think this is done until #13 is fully accomplished.

This is working fine in a Ludus script, as of https://alea.ludus.dev/scott/rudus/commit/6a0108997368c5949b06ee089c418888699c0bfd. Pulling from a simplified Prelude also works. There's some weirdness, though, in Prelude. I don't think this is done until #13 is fully accomplished.

scott commented

2024-12-12 06:21:30 +00:00

Forward declarations were not working. They are now, with 273267f61d. The long and short of it is that we need to update closed-over bindings after the function is defined.

Still: testing required.

Forward declarations were not working. They are now, with https://alea.ludus.dev/scott/rudus/commit/273267f61d8ddcdae9f3e331f0db172a5be14e9c. The long and short of it is that we need to update closed-over bindings after the function is defined. Still: testing required.

scott commented

2024-12-13 00:40:10 +00:00

Looks like it works now! Same commit as before to have gotten them right.

scott closed this issue

2024-12-13 00:40:10 +00:00

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