An interpeter for a subset of F# with Active Patterns

This is a homework for a functional programming course.

Language features done

• Standard data types:
  • bool
  • int
  • string
  • unit
  • list
  • option
• Standard binary and unary operators
• Recursive functions
  • First-class functions with partial application and mutual recursion
  • Closures
  • Carrying
• Anonymous functions
• Nested let bingings
• Standard function for integer printing
• Pattern matching
• Active Patterns
• Explicit type annotations

Implementation components

• AST
• Parser
• Type inferencer / checker
• Interpreter

There is also implemented:

• REPL
• Property-based testing: parser ∘ prettyPrinter ≡ id (parser and prettyPrinter composition produce the same AST) with qcheck

Quick start

Opam

1. Install opam

2. Install dependencies

    opam init --bare
    opam update
    opam switch create Fsharp --packages=ocaml-variants.4.14.2+options,ocaml-option-flambda --yes
    make deps

Opam will suggest you to update your bash (zsh) configuration to automatically set up the environment.

3. Run interpeter with

dune exec repl

And type

let (|Big|Small|) input = if input > 10 then Big(input) else Small(input);;
# val |Big|Small| : int -> Choice<Big (int), Small (int)> = <fun>

let f g x = match x with
| Big(x) -> Some(g x)
| _ -> None;;
# val f : (int -> '9) -> int -> '9 option = <fun>

let carried_f = f (fun x -> x * 2);;
# val carried_f : int -> int option = <fun>

carried_f 20;;
# val - : int option = Some 40

carried_f 5;;
# val - : int option = None

Or from file (file must not contain ;; separator) with

dune exec repl -from input.fs

Authors

• Ksenia Kotelnikova
• Gleb Nasretdinov