ocaml

Write a function named sum_prod that folds up a list on integers into a pair containing the sum and products. The type of this function will be int list -> int * int.

For example,

sum_prod [1;2;3] evaluates to (6,6).

sum_prod [1; 2; 3; 4] evaluates to (10, 24).

sum_prod [] evaluates to (0,1).