Monkey Language

This is a programming language which is designed as a learning project to learn how Interpreters and Compilers work.

Features

• C-like syntax
• variable building
• integers and booleans
• arithmetic expressions
• built-in functions
• first class and hight order functions
• closures
• a string data structure
• an array data structure
• a hash data structure

Example

let age = 33;
let name = "Dimitri";
let result = 10 * (20 / 2);

Arrays:

let myArray = [1, 2, 3, 4, 5];

Hashes:

let user = {"name": "Dimitri", "age": 33};

Accessing elements in arrays:

myArray[0]; // => 1

Accessing elements in hashes:

user["name"]; // => "Dimitri"

Binding function to statements:

let add = fn(a, b) { return a + b };

Implicit return:

let add = fn(a, b) { a + b };

Calling a function:

add(1, 2); // => 3

A more complex example:

let fibonacci = fn(x) {
  if (x == 0) {
    0
  } else {
    if (x == 1) {
      1
    } else {
      fibonacci(x - 1) + fibonacci(x - 2)
    }
  }
}

High order function:

let twice = fn(f, x){
  return f(f(x))
}

let addTwo = fn(x){
  return x + 2
}

twice(addTwo, 2) // => 6 : addTwo(addTwo(2))

let map = fn(arr,f){
  let iter = fn(arr, acc) {
    if(len(arr) == 0) {
      acc;
      } else {
        iter(rest(arr), push(acc, f(first(arr))))
      }
    };
  iter(arr, []);
  };

let timesTwo = fn(x) { x * 2 };
let a = [1, 2, 3, 4];
map(a, timesTwo) // [2, 4, 6, 8]

let reduce = fn(arr, initial, f) {
    let iter = fn(arr, result) {
      if(len(arr) == 0) {
        result;
      } else {
        iter(rest(arr), f(result, first(arr)));
      }
    };

    iter(arr, initial);
  };

let sum = fn(arr) {
    reduce(arr, 0, fn(initial, el) { initial + el } );
  };
let b = [1, 2, 3, 4, 5];

sum(b) // 15

Book

This project was built following the book Writing an Interpreter in Go by Thorsten Ball & Writing a Compiler in Go by Thorsten Ball.