wmfarmer% ocaml
        Objective Caml version 3.08.0

# let x = ref 8 ;;
val x : int ref = {contents = 8}
# let y = ref 9 ;;
val y : int ref = {contents = 9}
# x == y ;;
- : bool = false
# let x = y ;;
val x : int ref = {contents = 9}
# x == y ;;
- : bool = true
# x := 34 ;;
- : unit = ()
# !y ;;
- : int = 34
# let simple_sum m n =
  let accum = ref 0 in
  for i = m to n do
    accum := !accum + i ;
    print_int !accum ;
    print_newline ()
  done;
  !accum ;;
              val simple_sum : int -> int -> int = <fun>
# simple_sum 1 4 ;;
1
3
6
10
- : int = 10
# simple_sum (-4) 4 ;;
-4
-7
-9
-10
-10
-9
-7
-4
0
- : int = 0
# let sum f m n =
  let accum = ref 0 in
  for i = m to n do
    accum := !accum + (f i) ;
    print_int !accum ;
    print_newline ()
  done;
  !accum ;;
              val sum : (int -> int) -> int -> int -> int = <fun>
# sum (function x -> x * x) 0 3 ;;
0
1
5
14
- : int = 14
# sum (function x -> x * x -  4 + x) 0 3 ;;
-4
-6
-4
4
- : int = 4
# sum (function x -> x * x -  4 + x) 0 (-6) ;;
- : int = 0
# let super_sum zero add f m n =
  let accum = ref zero in
  for i = m to n do
    accum := add !accum (f i) ;
  done;
  !accum ;;
          val super_sum : 'a -> ('a -> 'b -> 'a) -> (int -> 'b) -> int -> int -> 'a =
  <fun>
# super_sum 0 ( + ) (function x -> x * x) 0 3 ;;
- : int = 14
# let g = (function x -> x * x) ;;
val g : int -> int = <fun>
# super_sum 0 ( + ) g 0 3 ;;
- : int = 14
# let factorial = super_sum 1 ( * ) (function x -> x) 1 ;;
val factorial : int -> int = <fun>
# factorial 4 ;;
- : int = 24
# factorial 5 ;;
- : int = 120
# super_sum "" ( ^ ) (function x -> "abc") 1 3 ;;
- : string = "abcabcabc"
# super_sum ;;
- : 'a -> ('a -> 'b -> 'a) -> (int -> 'b) -> int -> int -> 'a = <fun>
# let rec simple_sum_rec m n =
  if m > n 
  then 0
  else m + (simple_sum_rec (m + 1) n) ;;
      val simple_sum_rec : int -> int -> int = <fun>
# simple_sum_rec 0 100 ;;
- : int = 5050
# simple_sum_rec (-60) 60 ;;
- : int = 0
#