Wisp

A simple programming language that is implemented in JavaScript

Following program binds the value 10 to the variable x, then prints "large" if x is greater than 5, and "small" otherwise

do(define(x, 10),
   if(>(x, 5),
      print("large"),
      print("small")))

The >(x, 5) part of the previous program would be represented like this:

{
  type: "apply",
  operator: {type: "word", name: ">"},
  args: [
    {type: "word", name: "x"},
    {type: "value", value: 5}
  ]
}

Computes sum of numbers 1 to 10, expressed in wisp

run(`
    do(define(total, 0),
    define(count, 1),
    while(<(count, 11),
            do(define(total, +(total, count)),
                define(count, +(count, 1)))),
    print(total))
`);

// → 55

Defines a function, plusOne, that adds one to its argument, and calls it

run(`
    do(define(plusOne, fun(a, +(a, 1))),
    print(plusOne(10)))
`);
// -> 11

Defines a function, pow, that raises its first argument to the power of the second, and calls it

run(`
    do(define(pow, fun(base, exp,
        if(==(exp, 0),
            1,
            *(base, pow(base, -(exp, 1)))))),
    print(pow(2, 10)))
`);
// -> 1024

Defines a function, sum that computes the sum of an array of numbers, and calls it

run(`
    do(define(sum, fun(array,
         do(define(i, 0),
            define(sum, 0),
            while(<(i, length(array)),
              do(define(sum, +(sum, element(array, i))),
                 define(i, +(i, 1)))),
            sum))),
       print(sum(array(1, 2, 3))))
`);
// -> 6

Defines a function f that returns a function that adds its argument to the argument of f

run(`
    do(define(f, fun(a, fun(b, +(a, b)))),
       print(f(4)(5)))
`);
// -> 9

A comment in wisp is a line that starts with a hash sign (#), here is an example

run(`
    # This is a comment
    print(1)
`);
// -> 1