FooLang

Interpreter for a small ⚡functional language⚡.

Demo

Characteristics

• It's statically typed, but types are inferred rather than manually specifed.

• Haskell-like lambdas and function application:

  •   let identity x = x
    
      let lambdaId   = (\x -> x)
    
      let foo = 12 + (identity 1)
    

• It uses Hindley–Milner type system for type inference and polymorhphic types(✔)

  • let id = (\x -> x) - type of id: forall a => a -> a

  • let flip f x y = f y x - type of f: forall a b c => (b -> a -> c) -> (a -> b -> c). If you run that you will note that brackets are omitted, but since arrow is right-associative it's all the same.

• Two base types:

  • Int - as big as it needs to be,
  • Bool - True or False.

• Supports reccursion(✨):

    let rec fib n =
        if (n <= 0) then
            0
        else if (n == 1) then
            1
        else
            (fib (n - 1)) + (fib (n - 2))

• Interpreter supports few commands:
  • :type fibb - checks type of given identifier (in this case fibb),
  • :browse - prints list of defined functions with their respective types,
  • :quit - quits shell (same as CTRL-D),
  • :load path - loads module from a file,
  • :paste - enter multline mode.

For a code snippet look at 🔥🔥example.

Try it yourself

If you have stack (haskell build tool) installed on your machine just clone the repo and enter stack run.

You can also run stack install which will install the binaries in ~/usr/bin/. Then to run shell, simply eneter FooLang-exe.