/* print: |00011110| */
let
  function is_whitespace (char:string) : int =
    (char = "" | char = "\n" | char = " " | char = "\t")

  function testchar(char:string) =
    if is_whitespace(char) then print("1") else print("0")
in
    testchar("a");
    testchar("2");
    testchar("321");
    testchar("");
    testchar("\n");
    testchar(" ");
    testchar("\t");
    testchar("Recursion")
end