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From: Stefan Holdermans <stefan@vectorfabrics.com>
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To: Julien Signoles <julien.signoles@gmail.com>
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Subject: Re: [Caml-list] Converting "fun ... (type t) ..." into a caml < 3.12 code

Julien,

> How to convert the following ocaml 3.12 code into a typable ocaml < 3.12 code?


Coincidentally, earlier today, I ran into a situation not that different from the one you describe. I haven't come up with a satisfying solution yet.

> I have a solution using Obj. Is it possible without Obj?

Are you willing to share this solution?

> =====
> (* val f: 'a -> 'a list *)
> let f (type u) (x:u) =
>   let module S =
>     Set.Make(struct
>       type t = u
>       let compare = Pervasives.compare
>       let equal = ( = )
>     end)
>   in
>   S.elements (S.singleton x)
> =====
> 
> The contraints are:
> * do not change the type of f
> * use the functor Set.Make where type of keys are the same that type of x

Cheers,

  Stefan