fun sumupto (n: int) : int = 

            if (n = 0) then 0 else n + sumupto (n - 1) ;

fun maplist (f: 'a -> 'b, li: 'a list) : 'b list =
            
            case li of nil => nil | 

                   hl::tl => f(hl)::maplist(f,tl) ; 

(* 
- use "sum+map.ml" ;
[opening sum+map.ml]
val sumupto = fn : int -> int
val maplist = fn : ('a -> 'b) * 'a list -> 'b list
val it = () : unit

- sumupto(100) ;
val it = 5050 : int

- maplist(sumupto,[3,10,0]) ; 
(* = mapList(sumupto,3::10::0::nil) *)
val it = [6,55,0] : int list

- maplist(not, [true,false]) ;
val it = [false,true] : bool list

*)