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There were some concerns about facet types leaking out of generic code in return types. Some initial fixes for this were done in [PR #900](https://github.com/carbon-language/carbon-lang/pull/900), but there remain concerns, for example when associated types are involved. In particular, given an interface method with return type using an associated type, as in: ``` interface Deref { let Result:! Type; fn DoDeref[me: Self]() -> Result; } class IntHandle { impl as Deref { let Result:! Type = i32; fn DoDeref[me: Self]() -> Result { ... } } } ``` Since `Result` has type `Type`, we had the problem that `IntHandle.DoDeref` would have to return `i32 as Type`, instead of the desired `i32`. We also think we can simplify the model by eliminating the facet type concept and syntax. This proposal removes facet types, introduces archetypes in their place, clarifies how associated types work outside of a generic function, and specifies how a generic `let` statement in a function body works. Co-authored-by: Wolff Dobson <wolffg@users.noreply.github.com> Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Generics
This directory contains the collection of documents describing the generics feature of Carbon:
- Overview - A high-level description of the generics design, with pointers to other design documents that dive deeper into individual topics.
- Goals - The motivation and principles guiding the design direction.
- Terminology - A glossary establishing common terminology for describing the design.
- Detailed design - In depth description of how generic type parameters work.
Rejected alternatives- not implemented yet