https://github.com/kseo/poly_constraints

Hindley-Milner type inference using constraints
https://github.com/kseo/poly_constraints

Last synced: 10 days ago
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Hindley-Milner type inference using constraints

• Host: GitHub
• URL: https://github.com/kseo/poly_constraints
• Owner: kseo
• License: mit
• Created: 2017-01-02T16:20:40.000Z (almost 8 years ago)
• Default Branch: master
• Last Pushed: 2017-01-02T16:21:05.000Z (almost 8 years ago)
• Last Synced: 2024-10-12T23:22:30.369Z (26 days ago)
• Language: Haskell
• Size: 13.7 KB
• Stars: 48
• Watchers: 2
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
Poly

====

A simple ML dialect with definitions, let polymorphism and a fixpoint operator.

Uses syntax directed HM type inference.

To compile and run:

```shell

$ cabal run

```

Usage:

```ocaml

Poly> let i x = x;

i : forall a. a -> a

Poly> i 3

3

Poly> :type i

i : forall a. a -> a

Poly> :type let k x y = x;

k : forall a b. a -> b -> a

Poly> :type let s f g x = f x (g x)

s : forall a b c. ((a -> b) -> c -> a) -> (a -> b) -> c -> b

Poly> :type let on g f = \x y -> g (f x) (f y)

on : forall a b c. (a -> a -> b) -> (c -> a) -> c -> c -> b

Poly> :type let let_bound = i (i i) (i 3)

let_bound : Int

Poly> :type let compose f g = \x -> f (g x)

compose : forall a b c. (a -> b) -> (c -> a) -> c -> b

Poly> let rec factorial n = 

  if (n == 0) 

  then 1

  else (n * (factorial (n-1)));

```

Notes

=====

Top level let declarations are syntactic sugar for nested lambda. For example: 

```ocaml

let add x y = x + y;

```

Is semantically equivalent to:

```ocaml

let add = \x -> \y -> x + y;

```

Top level Let-rec declarations are syntactic sugar for use of the ``fix``

operator. For example:

```ocaml

let rec factorial n = if (n == 0) then 1 else (n * (factorial (n-1)));

```

Is semantically equivalent to:

```ocaml

let factorial = fix (\factorial n -> if (n == 0) then 1 else (n * (factorial (n-1))));

```

License

=======

Released under MIT license.