diff --git a/src/chalk-overview.md b/src/chalk-overview.md index cd2c98b8..926c7f5a 100644 --- a/src/chalk-overview.md +++ b/src/chalk-overview.md @@ -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 any of the information is inconsistent with the code or outdated, please -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 { ... }` is represented in the code using the [`Binders` 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 Clone for Vec {} ``` -We generate: +We generate the following program clause: ```rust,ignore forall { (Vec: Clone) :- (T: Clone) } @@ -102,22 +102,23 @@ For example, if you have a type like `Foo`, 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.