higuma

// JavaScript Array permutation generator
// (optimized from CoffeeScript output: see ArrayPermutation.coffee)
(function() {
  var generatePermutation = function(perm, pre, post, n) {
    var elem, i, rest, len;
    if (n > 0)
      for (i = 0, len = post.length; i < len; ++i) {
        rest = post.slice(0);
        elem = rest.splice(i, 1);
        generatePermutation(perm, pre.concat(elem), rest, n - 1);

higuma

# internal: generate permutation recursively
generatePermutation = (perm, pre, post, n) ->
  if n > 0
    for i in [0...post.length]
      rest = post.slice 0
      elem = rest.splice i, 1
      generatePermutation perm, pre.concat(elem), rest, n - 1
  else
    perm.push pre
  return