last item. no output

Hello,

I try to solve the first challenge from the 99 ocaml problems where I 
have to find the last item in a list.

So I have this :

let rec last list =
    match list with
    | [] -> []
    | [x] -> x
    | hd :: tl  -> last tl
    ;;

I saved it into a file called test.ml and build it with corebuild 
test,native.
But when I do ,/test.native [] or ./test.native [1] I see total no output.

Roelof