monk-rs

An interpreter for the Monkey Language written in Rust.

The language comes from the book Writing An Interpreter In Go by Thorsten Ball.

This version contains more features than the original book and supports loops and bitwise operations. Also, the language is proven to be turing complete.

Language features

Integer, boolean, string, array and hash data types

let age = 1;
let isTrue = true;
let name = "Monkey";
let array = [1, 2, 3, 4];
let hash = {"one": 1, "two": 2};

Basic operations

let result = 1 + 2 * 3 / 4 - 5;
let isTrue = 1 < 2;
let isFalse = !isTrue;
"Hello" + " " + "World";

Logical operations

1 == 1 == true
1 != 2 == true
12 || -1 == true
1 && 0 == false
true && true == true
true && false == false
true || false == true

Bitwise operations

1 & 3 == 1
1 | 2 == 3
1 ^ 3 == 2
3 << 2 == 12
4 >> 1 == 2

Conditionals

let x = if (10 < 5) {
    10;
} else if (10 > 5) {
    5;
} else {
    0;
}

While loops

let i = 0;
let j = while (i < 2) {
    i = i + 1;
}

For loops

let sum = 0;
for (let i = 0; i < 11; i = i + 1) {
    let sum = sum + i;
}
sum == 55

Functions and closures

let adder = fn(x) {
    fn (y) {
        return x + y;
    };
};

let addTwo = adder(2);
addTwo(5) == 7;

Built-in Functions

print(arg1, arg2, ...)

len("string") == 6

len(["a", "b"]) == 2

first([1, 2, 3]) == 1

rest([1, 2, 3]) == [1, 2, 3]

last([1, 2, 3]) == 3

push([1, 2], 3) == [1, 2, 3]

Getting started

Using repl

$ make repl

Running examples

$ cargo run -- examples/<filename>.mk