This is in Ocaml

Write a function filter: (a -> bool) -> a list -> a list. The call filter f l should return l with all and only the items for which f returns true; these items should appear in the same order in which they appear in the original list. Some examples:

filter (fun x -> x > 2) [5; 3; 1; 2; 4] = [5; 3; 4]

filter (fun x -> x > 5) [5; 3; 1; 2; 4] = []

Will thumb up thanks!