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@ -2,8 +2,8 @@
> Chalk is under heavy development, so if any of these links are broken or if
> any of the information is inconsistent with the code or outdated, please
> [open an issue][rustc-issues] so we can fix it. If you are able to fix the issue yourself, we would
> love your contribution!
> [open an issue][rustc-issues] so we can fix it. If you are able to fix the
> issue yourself, we would love your contribution!
[Chalk][chalk] recasts Rust's trait system explicitly in terms of logic
programming by "lowering" Rust code into a kind of logic program we can then
@ -42,7 +42,7 @@ Rust-like syntax.
The parser takes that syntax and produces an [Abstract Syntax Tree (AST)][ast].
You can find the [complete definition of the AST][chalk-ast] in the source code.
The syntax contains things from Rust that we know and love for example traits,
The syntax contains things from Rust that we know and love, for example: traits,
impls, and struct definitions. Parsing is often the first "phase" of
transformation that a program goes through in order to become a format that
chalk can understand.
@ -67,14 +67,14 @@ essentially one of the following:
* `forall<T> { ... }` is represented in the code using the [`Binders<T>`
struct][binders-struct].
This is the phase where we encode the rules of the trait system into logic. For
example, if we have:
Lowering is the phase where we encode the rules of the trait system into logic.
For example, if we have the following Rust:
```rust,ignore
impl<T: Clone> Clone for Vec<T> {}
```
We generate:
We generate the following program clause:
```rust,ignore
forall<T> { (Vec<T>: Clone) :- (T: Clone) }
@ -102,22 +102,23 @@ For example, if you have a type like `Foo<Bar>`, we would represent `Foo` as a
string in the AST but in `ir::Program`, we use numeric indices (`ItemId`).
In addition to `ir::Program` which has "rust-like things", there is also
`ir::ProgramEnvironment` which is "pure logic". The main field in that is
`ir::ProgramEnvironment` which is "pure logic". The main field in that struct is
`program_clauses` which contains the `ProgramClause`s that we generated
previously.
## Rules
The `rules` module works by iterating over every trait, impl, etc. and emitting
the rules that come from each one. The traits section of the rustc-guide (that
you are currently reading) contains the most up-to-date reference on that.
the rules that come from each one. See [Lowering Rules][lowering-rules] for the
most up-to-date reference on that.
The `ir::ProgramEnvironment` is created [in this module][rules-environment].
## Testing
TODO: Basically, [there is a macro](https://github.com/rust-lang-nursery/chalk/blob/94a1941a021842a5fcb35cd043145c8faae59f08/src/solve/test.rs#L112-L148)
that will take syntax and run it through the full pipeline described above.
that will take chalk's Rust-like syntax and run it through the full pipeline
described above.
[This](https://github.com/rust-lang-nursery/chalk/blob/94a1941a021842a5fcb35cd043145c8faae59f08/src/solve/test.rs#L83-L110)
is the function that is ultimately called.