rmonkey

Rust implementation of the programming language Monkey that lives in books

Features

• C-like Syntax
• Variable bindings
• Integer and Boolean
• Built-in data structures(String, Array, Hash)
• Arithmetic expressions
• If expressions
• Built-in functions
• First-class and higher-order functions
• Support closures

overview

• Literal
  • Integer
  • Boolean
  • String
  • Array
  • Hash
  • Function
• Built-in functions

Literal

Integer

Integer represents 2^-63(-9223372036854775808) to 2^63(9223372036854775807).

example

1;
-1;
101;
9223372036854775807;

Boolean

Boolean represents only two possible value, true or false.

example

true;
false;
let flag = !true;

String

String represents the array of characters.Double-Quoted string is only available.

example

"Hello World"
"foo" + "bar" + "baz"

Array

Array represents a collection of elements.

example

let array = [1, 2, 3, 4, 5]
array[0] // 1
array[1+1] // 3

let array = [1, "foo", true, fn(a){a}]
array[4](2)

Hash

Hash represents the data structure that holds a pair of key and value.

example

let hash = {"foo":1, "bar": 2, "baz": "hello", 100: "world"};
hash["foo"]
hash[99 + 1]

Function

example

fn add(x, y){
    return x + y;
}

let fibonacci = fn(x) {
  if (x == 0) {
    0;
  } else {
    if (x == 1) {
      1;
    } else {
      fibonacci(x - 1) + fibonacci(x - 2);
    }
  }
};
fibonacci(5);

let twice = fn(f, x) { return f(f(x));};
let addTwo = fn(x) { return x + 2;};
twice(addTwo, 2);

Built-in functions

puts(<arg1>, <arg2>, ...): void

puts("string");
puts(2);

len(<arg>): Integer

len([0,1,2,3,4])
len("Hello World")

first(<arg>): any

first([0,1,2,3]) // => 0
first(["string", 0, true]) // "string"

last(<arg>): any

last([0,1,2,3,4]) // => 4

rest(<arg>): Array

rest([0,1,2]) // => [1,2]

push(<arg1>, <arg2>): Array

push([0,1,2,3,4], 5)

Credits

• Writing Interpreter In Go