Tell HN: We are trying to get tail calls into the WebAssembly standard

  let sum list =
    let rec loop a = function
      | [] -> a
      | x::xs -> loop (a+x) xs
    in
    loop 0 list

  let rec even_then b n =
    if n = 0 then b else odd_then (not b) (n - 1)
  and odd_then b n =
    if n = 1 then b else even_then (not b) (n - 1)

  fn even_then_or_odd_then(which_function, b1, n1, b2, n2) {
    loop {
      match(which_function) {
        Even => {
          if n1 = 0 { return b1 }
          else {
            b2 = not(b1);
            n2 = n1 - 1;
            which_function = Odd;
          }
        },
        Odd => { similar }
      }
    }
  }
  
  fn even_then(b,n) {
    even_then_or_odd_then(Even, b, n, null, null)
  }
  
  ...

  let parse_both p1 p2 =
    fun buf pos success ->
      p1 buf pos (fun pos r ->
        p2 buf pos (fun pos r2 ->
          success pos (r, r2)))
  ;;

  void foo(...) {
    ...
    bar(x,y,z); // <= a tail call
  }

  int foo(...) {
    ...
    return bar(x,y,z); // <= still a tail call
  }

  uint factorial(uint n) {
    uint acc = 1;
    for(; n > 0; n--) {
      acc *= n;
    }
    return acc;
  }
  uint factorial(uint n, uint acc = 1) {
    if (n == 0) return acc;
    return factorial(n - 1, acc * n);
  }