# let x = ref 42;;
val x : int ref = {contents = 42}
# x := 100/4;;
- : unit = ()
# let y = !x + 1;;
val y : int = 26
# print_int 3;;
- : unit = <unknown constructor>
# print_string "Hello";;
- : unit = <unknown constructor>
# print_string "x = ";
# print_int !x;
# print_newline ();;
- : unit = ()
# Printf.printf "x = %d. Bye %s\n" !x "John";;
- : unit = ()