https://github.com/andreypopp/type-systems

Playing with type systems
https://github.com/andreypopp/type-systems

hindley-milner ocaml type-inference type-systems typeclasses

Last synced: 6 days ago
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Playing with type systems

• Host: GitHub
• URL: https://github.com/andreypopp/type-systems
• Owner: andreypopp
• Created: 2021-10-15T18:59:35.000Z (over 3 years ago)
• Default Branch: main
• Last Pushed: 2024-12-29T19:36:39.000Z (23 days ago)
• Last Synced: 2025-01-08T12:52:16.601Z (13 days ago)
• Topics: hindley-milner, ocaml, type-inference, type-systems, typeclasses
• Language: OCaml
• Homepage:
• Size: 199 KB
• Stars: 48
• Watchers: 4
• Forks: 2
• Open Issues: 1
• Metadata Files:
  • Readme: README.md

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README

        
# type-systems

- `algo_w` - Algorithm W extended with "Extensible Records with Scoped Labels"

  and Multi Parameter Typeclasses.

  This follows closely [tomprimozic/type-systems] and then [THIH][] (Typing

  Haskell in Haskell). Note that this tries to support multi-parameter typeclasses

  (MPTC) but generalization is currently buggy for typeclasses with multiple parameters.

  See `hmx_tc` implementation for the bug-free HM + MPTC implementation.

- `hmx` - [HM(X)][] style implementation of Hindley Minler type inference.

  The main idea is to introduce constraint language and split the algo into two

  phases — first generate constraints from terms, then solve those constraints.

  This implementation also does elaboration, the `infer` function has the

  following signature:

  ```

  val infer : env:Env.t -> expr -> (expr, Error.t) result

  ```

  That means that `infer` returns not just the type of the expression but an

  elaborated expression (an original expression annotated with types).

  The elaboration mechanism is shamelessly stolen from [inferno][].

- `hmx_tc` - extends [HM(X)][] with Multi-Parameter Typeclasses (MPTC).

  

  Type inference and elaborator are implemented but the environment construction

  doesn't check for overlapping instances yet.

# Development

```

make init

make build

make test

```

# References

- https://en.wikipedia.org/wiki/Hindley–Milner_type_system

- https://www.microsoft.com/en-us/research/wp-content/uploads/2016/02/scopedlabels.pdf

- https://www.cs.tufts.edu/~nr/cs257/archive/martin-odersky/hmx.pdf

- https://web.cecs.pdx.edu/~mpj/thih/thih.pdf

- https://github.com/tomprimozic/type-systems

- https://gitlab.inria.fr/fpottier/inferno/

- https://github.com/naominitel/hmx

[HM(X)]: https://www.cs.tufts.edu/~nr/cs257/archive/martin-odersky/hmx.pdf

[inferno]: https://gitlab.inria.fr/fpottier/inferno/

[THIH]: https://web.cecs.pdx.edu/~mpj/thih/thih.pdf

[tomprimozic/type-systems]: https://github.com/tomprimozic/type-systems