| 30 Mar 2024 |
 jimb | But if Arena were published as a "general purpose" crate, I can imagine some energetic person showing up with a tagging scheme or something something branded lifetimes something something invariant subtyping | 22:11:08 |
| jimb | and that's just a distraction. There's no need for that in our context. | 22:11:24 |
| jimb | So I think if we pull it out, there needs to be some messaging around what its scope is. It supports wgpu, period. | 22:11:57 |
| jimb | * So I think if we pull it out of Naga, there needs to be some messaging around what its scope is. It supports wgpu, period. | 22:12:07 |
| jimb | It's so simple, if it doesn't suit your needs, write your own. | 22:12:25 |
| jimb | * "It's so simple, if it doesn't suit your needs, write your own." would be our message to outside users. | 22:12:39 |
| jimb | I guess the crate should be named wgpu_arena or something, so that we don't appear to be offering a competitive alternative to other arena-ish things on crates.io. | 22:13:08 |
| jimb | The other wrinkle: Naga's Arenas store source location spans, too. | 22:15:14 |
| jimb | No, we don't really need the details tracked. We know that Naga's current analysis is conservative and non-standards-compliant, and we have it on our roadmap to be entirely replaced. | 22:30:06 |
| jimb | In reply to @eddyb:matrix.org
also "unique" stuff is usually called "interner" tho I wouldn't be surprised if there's a few more names for that idea I have no attachment to the name. | 22:31:02 |
 crowlkats | https://github.com/gfx-rs/wgpu/pull/5459 | 23:04:52 |
| 31 Mar 2024 |
 lylythechosenone | good point | 01:23:10 |
|  imbris changed their profile picture. | 15:27:44 |
| 2 Apr 2024 |
 ErichDonGubler | In reply to @jimb:mozilla.org
But if Arena were published as a "general purpose" crate, I can imagine some energetic person showing up with a tagging scheme or something something branded lifetimes something something invariant subtyping Hot take: use a newtype. | 16:50:26 |
| jimb | It doesn't work out quite the way you'd hope. | 16:51:03 |
| jimb | So you've got your function arenas, Function::expressions, and your global arena, Module::global_expressions. | 16:51:38 |
| jimb | Both of them are indexed by Handle<Expression> | 16:51:50 |
| jimb | You can say, okay, struct GlobalExpression(Expression); and then have Module::global_expressions be an Arena<GlobalExpression>. | 16:52:42 |
| jimb | But the Expression variants inside that GlobalExpression still hold Handle<Expression> handles for their subexpressions. | 16:53:19 |
| jimb | So as soon as you get any data out of the arena, it's not just that you've lost typing information - it's incorrectly typed, because Handle<Expression> is what you were using for Function::expressions. | 16:54:00 |
| jimb | Okay, so, make Expression generic over a type H for subexpression handles. But now the type of Function::expressions is Arena<FunctionExpression>, where struct FunctionExpression(Expression<FunctionExpression>);. | 16:55:52 |
| jimb | and at this point you say, I have taken a wrong turn somewher | 16:56:24 |
| jimb | * and at this point you say, I have taken a wrong turn somewhere | 16:56:27 |
| jimb | or at least I do | 16:56:31 |
| jimb | * So as soon as you get any data out of the arena, you've lost typing information. | 16:57:28 |
| jimb | * So as soon as you get any data out of the arena, you've lost the newtype. | 16:57:40 |
| jimb | Also:
use std::marker::PhantomData;
struct Handle<T>(usize, PhantomData<T>);
enum Expr<H> {
Num(i32),
Add(Handle<Expr<H>>, Handle<Expr<H>>),
}
| 17:00:21 |
| jimb | I suppose I could fix this, but again, it feels like I made a wrong turn:
error[E0392]: parameter `H` is never used
--> src/lib.rs:5:11
|
5 | enum Expr<H> {
| ^ unused parameter
|
= help: consider removing `H`, referring to it in a field, or using a marker such as `PhantomData`
= help: if you intended `H` to be a const parameter, use `const H: usize` instead
| 17:00:53 |
| jimb | You can feel your Haskell muscles warming up and it's a bad sign | 17:01:14 |
| ErichDonGubler | * Hot take: use a newtype? | 17:51:25 |
