How to write a loop over a given list in ATS?

Question

Suppose I have a list xs. How do I write the following style of loop in ATS:

foreach x in xs do process(x)

Answer 1

You can use the old DIY-style (also: the classical ATS style), that is to say, using a tail-recursive function. Here's an example:

extern
fun
process (x: int): void
fun
loop {n:int} (xs: list(int, n)): void =
  case+ xs of
  | list_nil () => ()
  | list_cons (x, xs1) => let
    val () = process (x)
  in
    loop (xs1)
  end
// end of [loop]

You can run the full code online

I think that this approach is preferable if none of the combinators or template functions provided in the libraries such as ATSLIB is suitable for your case.