TailRecursiveRange.elm

range : number -> number -> List number
range s e =
    if s < e then
        rangeWith (-) (<) e s []
    else
        rangeWith (+) (>) e s []

rangeWith : (number -> number -> number) -> (number -> number -> Bool) -> number -> number -> List number -> List number
rangeWith modifyCount compare s e acc =
    if compare s e then
        acc
    else
        rangeWith modifyCount compare (modifyCount s 1) e (s :: acc)

ZZZOutput.js

var _user$project$Range$rangeWith = F5(
	function (modifyCount, compare, s, e, acc) {
		rangeWith:
		while (true) { // this is tail-recursive optimisation
			if (A2(compare, s, e)) {
				return acc;
			} else {
				var _v0 = modifyCount,
					_v1 = compare,
					_v2 = A2(modifyCount, s, 1),
					_v3 = e,
					_v4 = A2(_elm_lang$core$List_ops['::'], s, acc);
				modifyCount = _v0;
				compare = _v1;
				s = _v2;
				e = _v3;
				acc = _v4;
				continue rangeWith;
			}
		}
	});
var _user$project$Range$range = F2(
	function (s, e) {
		return (_elm_lang$core$Native_Utils.cmp(s, e) < 0) ? A5(
			_user$project$Range$rangeWith,
			F2(
				function (x, y) {
					return x - y;
				}),
			F2(
				function (x, y) {
					return _elm_lang$core$Native_Utils.cmp(x, y) < 0;
				}),
			e,
			s,
			_elm_lang$core$Native_List.fromArray(
				[])) : A5(
			_user$project$Range$rangeWith,
			F2(
				function (x, y) {
					return x + y;
				}),
			F2(
				function (x, y) {
					return _elm_lang$core$Native_Utils.cmp(x, y) > 0;
				}),
			e,
			s,
			_elm_lang$core$Native_List.fromArray(
				[]));
	});