lucassus / lucky-script

My Own Simple Programming Language

Basic usage

1. yarn install
2. yarn lint and yarn test
3. ts-node src/repl.ts to start the REPL

➜ ts-node src/repl.ts
> 1 + 2 * 3 ** 5.2
606.4252366531416

> function add(a, b) { return a + b }
undefined
> add(1, 2)
3

> function asdf
SyntaxError: Expected '(' delimiter but got 'End' delimiter.

> function foo() asdf
SyntaxError: Expected '{' delimiter but got 'Identifier' literal.

Functions

function add(a, b) {
  return a + b
}

add(1, 2) * 2 - 1  # Evaluates to 5

It supports basic if statements and the recursion:

function fib(n) {
  if (n < 2) {
    return n
  }
  
  return fib(n - 2) + fib(n - 1)
}

Height order functions are also supported:

foo = function() { 
  x = 1
  
  # Yes! It's a function that returns another function ;)
  return function() {
    return x + 2
  }
}

bar = foo()
bar()

Variables scopes and closures

a = 1

function foo() {
  a = 2 # Should replace value in the parent scope
  b = 1 # Should be accessible only in the current scope
  
  function bar() {
    c = 3 # Should be accessible only in the current scope
    return a + b + c
  }
  
  return bar()
}

d = foo()

Dynamic scopes

a = 1

function add() {
  # Currently a is 1, but later its value will be changed
  
  return a + 1
}

firstResult = add() 
# => 2

a = 2
secondResult = add() 
# => 3