README.md

Sub-OCaml

Interpreter for a subset of the OCaml language.
This project did not intend to use idiomatic rust code. I mainly explored the syntactical possibilites of matches, recursion etc. for rust.

     

Usage

You can use the REPL to directly execute code and try it out

Dependencies

This project has no external dependencies.

Features

Features	Status
Lexer	✅
Parser	✅
Typechecker	✅
Evaluator	✅

Examples

1

let x = 5 in x

Lex result:

[LET, VAR("x"), EQ, CON(ICON(5)), IN, VAR("x")]

Parse result:

Let("x", Con(Icon(5)), Var("x"))

Typechecker result:

Int

Evaluator result:

IntValue(5)

---

2

let rec fib (a:int) : int -> int -> int = fun (b:int) -> fun (n:int) -> if n <= 0 then a else fib (b) (a+b) (n-1) in fib 0 1 8

Lex result:

[LET, REC, VAR("fib"), LP, VAR("a"), COL, VAR("int"), RP, COL, VAR("int"), ARR, VAR("int"), ARR, VAR("int"), EQ, LAM, LP, VAR("b"), COL, VAR("int"), RP, ARR, LAM, LP, VAR("n"), COL, VAR("int"), RP, ARR, IF, VAR("n"), LEQ, CON(ICON(0)), THEN, VAR("a"), ELSE, VAR("fib"), LP, VAR("b"), RP, LP, VAR("a"), ADD, VAR("b"), RP, LP, VAR("n"), SUB, CON(ICON(1)), RP, IN, VAR("fib"), CON(ICON(0)), CON(ICON(1)), CON(ICON(8))]

Parse result:

Letrecty("fib", "a", Int, Arrow(Int, Arrow(Int, Int)), Lamty("b", Int, Lamty("n", Int, If(Oapp(Leq, Var("n"), Con(Icon(0))), Var("a"), Fapp(Fapp(Fapp(Var("fib"), Var("b")), Oapp(Add, Var("a"), Var("b"))), Oapp(Sub, Var("n"), Con(Icon(1))))))), Fapp(Fapp(Fapp(Var("fib"), Con(Icon(0))), Con(Icon(1))), Con(Icon(8))))

Typechecker result:

Int

Evaluator result:

IntValue(21)

Example usage code:

use Sub_OCaml::{lexer, parse, ty, type_check};

fn main() {
    let src = "let x = 5 in x";
    println!("Code: {} \n", src);
    let tokenlist: Vec<Token> = lexer(&src).unwrap();
    println!("After Lex: {:?} \n", tokenlist);
    let ast = parse(tokenlist).unwrap().0;
    println!("After Parse: {:?} \n", ast);
    let mut map: BTreeMap<String, ty> = BTreeMap::new();
    let typed = super::type_check(&mut map, ast).unwrap();
    println!("After Typecheck: {:?}", typed);
}