how to write this code by standard meta language(ML)?

Write a function replace that takes an index n, a value v, and a list L and returns a (new) list which is the same as L, except that nth element is v. Assume 0 based indexing. Also assume that the index, n, is at least 0 and smaller than the length of the list L The type of replace should be int -> 'a 'a list ->'a list. Examples: > replace 3 40 [1, 2, 3, 4, 5, 6] [1,2,3,40,5,6 replace 0 "X" ["a", "b", "c","d