Question

I am new to OCaml, so I am learning the basics. I am writing a function that determines whether a list contains a given integer.

let rec int_member (x: int) (l: int list) : bool 
begin match l with
| [] -> false
| hd :: rest -> x = hd || int_member rest x
end

as a test case…

let test (): bool =
(int_member 1 [1;2;3]) = true
;; run_test "contains 1 [1;2;3]" test

I am getting an error saying that “this expression has type int list but an expression was expected of type int”. How can I fix this?

Answer 1

If you look at your recursive call, you should see that you’re not passing the arguments quite right! Otherwise this code is quite good. (I see a missing =, and also using begin and end isn’t very idiomatic OCaml here. You can just leave them out.)