fizzbuzz.js

var Fizz = {
  toString: function(){ return 'Fizz' }
}
var Buzz = {
  toString: function(){ return 'Buzz' }
}
var FizzBuzz = {
  toString: function(){ return 'FizzBuzz' }
}

function fizzbuzz(n) {
  return n % 15 === 0?  FizzBuzz
  :      n % 3 === 0?   Fizz
  :      n % 5 === 0?   Buzz
  :      /* _ */        n
}

function iterate(n, f) {
  return [n, () => iterate(n, f(n))]
}

function map(f, xs) {
  if (xs.length === 0) {
    return null
  } else {
    var [h, t] = xs;
    return [f(h), map(f, t())]
  }
}

function take(n, xs) {
  if (n === 0 || xs.length === 0) {
    return null
  } else {
    var [h, t] = xs;
    return [h, take(n - 1, t())]
  }
}

function toArray(xs) {
  if (xs.length === 0) {
    return []
  } else {
    var [h, t] = xs;
    return [h].concat(toArray(t()))
  }
}

function range(start, end) {
  if (start === end) {
    return []
  } else {
    return [start].concat(range(start, end))
  }
}

// -- iterative
range(1, 100).map(fizzbuzz).join(', ')

// -- Corecursive
var nats = iterate(0, x => x + 1)
toArray(take(100, map(fizzbuzz, nats))).join(', ')