[Caml-list] type annotations for function values

[Caml-list] type annotations for function values

[fis]

hi all,

as the grammar and type system of ocaml are so sophisticated, i am
often having trouble narrowing down the source of an error message.
the answer are of course type annotations, "i know this function here
must have this type, trust me", something of that ilk.

now this is easy:

  let f (x : float) (y : float) = 3 in 4;;

but what do i do if i want to write down an explicit type for f?  the
only thing i found that works is

  let f : (float -> float -> int) = (fun x y -> 3) in 4;;

which is horribly inelegant.  why can't i do something like this?

  let (f : (float -> float -> int)) x y = 3 in 4;;
  let ((f x y) : (float -> float -> int)) = 3 in 4;;
  let ((f (x : float) (y : float)) : int) = 3 in 4;;

the last one seems wrong, but anyway, i am still hoping that something
like this exists.

thanks,
matthias

-------------------
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

Re: [Caml-list] type annotations for function values

[Kenneth Knowles]

The syntax for what you want is:

# let f (x : float) (y : float) : int = 3 in 4;;

You almost had it:

On Thu, Mar 25, 2004 at 08:42:54PM +0100, fis@wiwi.hu-berlin.de wrote:
>   let ((f (x : float) (y : float)) : int) = 3 in 4;;


Kenn

-------------------
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