monkey-interpreter

README

Monkey Programming Language

Welcome to the Monkey programming language! This project is an implementation based on the concepts taught in the books Writing An Interpreter In Go and Writing A Compiler In Go by Thorsten Ball.

About Monkey

Monkey is a programming language that supports various data types, functions, conditionals, recursion, and closures. Here's an overview of its features:

Integers & Arithmetic Expressions

// Integers & arithmetic expressions...
let version = 1 + (50 / 2) - (8 * 3);

Strings

// ... and strings
let name = "The Monkey programming language";

Booleans

// ... booleans
let isMonkeyFastNow = true;

Arrays & Hash Maps

// ... arrays & hash maps
let people = [{"name": "Anna", "age": 24}, {"name": "Bob", "age": 99}];

It also has functions!

User-defined Functions

// User-defined functions...
let getName = fn(person) { person["name"]; };
getName(people[0]); // => "Anna"
getName(people[1]); // => "Bob"

Built-in Functions

// and built-in functions
puts(len(people));  // prints: 2

Conditionals and Recursion

Monkey supports conditionals, implicit and explicit returns, and recursive functions. Here's an example of a recursive function to compute Fibonacci numbers:

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

Closures

The crown jewel in every Monkey implementation is closures:

// `newAdder` returns a closure that makes use of the free variables `a` and `b`:
let newAdder = fn(a, b) {
    fn(c) { a + b + c };
};
// This constructs a new `adder` function:
let adder = newAdder(1, 2);

adder(8); // => 11