On Fri, 2 Jul 2004, Martin Berger wrote:

> now i annotate the definition above with the types just
> inferred:
> 
>      let rec y  ( f : ( 'a -> 'b ) -> 'a -> 'b )
>             : ( ( 'a -> 'b ) -> 'a -> 'b ) -> 'a -> 'b
>        = f (fun x -> (y f) x );;

This is where your mistake is.  Don't duplicate the type of f.  Instead, 
you should have done:

let rec y (f : ('a -> 'b) -> 'a -> 'b) : 'a -> 'b = f (fun x -> (y f) x);;

And now it works:
$ ocaml
        Objective Caml version 3.07
 
# let rec y (f : ('a -> 'b) -> 'a -> 'b) : 'a -> 'b = f (fun x -> (y f) 
x);;
val y : (('a -> 'b) -> 'a -> 'b) -> 'a -> 'b = <fun>
#

-- 
"Usenet is like a herd of performing elephants with diarrhea -- massive,
difficult to redirect, awe-inspiring, entertaining, and a source of
mind-boggling amounts of excrement when you least expect it."
                                - Gene Spafford 
Brian

-------------------
To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr
Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/
Beginner's list: http://groups.yahoo.com/group/ocaml_beginners