curry : (('a * 'b) -> 'c) -> 'a -> 'b -> 'c
curry f x y = f(x,y)
A call curry f never fails; however, curry f x y fails if f (x,y) fails.
- val increment = curry op+ 1; > val it = increment = fn : int -> int - increment 6; > val it = 7 : int