Demonstration of how to write OCaml source files so that no double semicolons are ever required

no_need_for_double_semicolons_in_source_files.ml

let print_line =
  let line = String.make 80 '-' in
  fun () -> print_endline line

module UglyA =
  struct
    open Printf

    let x = 5;;

    printf "Hello from UglyA!\n";
    printf "UglyA says x is %d\n" x;;

    let x = 9;;
    printf "UglyA says new x is %d\n" x;
    print_line ()
  end

module UglyB =
  struct
    open Printf;;

    printf "Hello from UglyB!\n";;

    let x = 18;;

    printf "UglyB says x is %d\n" x;
    print_line ()
  end

module Pretty =
  struct
    open Printf

    let x = 39
    let y = 1
    let z = 2

    let () =
      let sum = x + y + z in
      printf "Hello from Pretty!\n";
      printf "Pretty thinks that x + y + z = %d!\n" sum

    let () =
      printf "Pretty wants more side effects here\n";
      print_line ()
  end