You're probably trying to use functors ( http://caml.inria.fr/pub/docs/manual-ocaml/manual004.html#toc15 ). Though your example code isn't doing anything in particular.

On 14 February 2012 00:33, Andre Nathan <andre@digirati.com.br> wrote:
Hello

I have some code that behaves like the following.

module M = struct
 type ('a, 'b) ops = {
   bar_of_foo : 'a -> 'b;
   foo_of_bar : 'b -> 'a
 }

 let foo ops x = ops.bar_of_foo x
 let bar ops x = ops.foo_of_bar x
end

type foo = A | B
type bar = C | D

let ops = {
 M.bar_of_foo = (function A -> C | B -> D);
 M.foo_of_bar = (function C -> A | D -> B)
}

let () =
 match M.foo ops A with
 | C -> ()
 | D -> ()

The idea is to parametrize the behavior of some module M on two types and a set of operations involving these two types, with the catch that I want to keep the ability to pattern-match on the possible values of these types in the code that handles the return values from the functions exported by M.

With the scheme above I can do this, but passing a table of functions around doesn't look very nice. Is there any way I can use functors to do what this code does, while still being able to use pattern-matching? Would I have to resort to objects to be able to do this?

Thanks in advance,
Andre

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