From: Jacques Garrigue <garrigue@math.nagoya-u.ac.jp>
To: Lauri Alanko <la@iki.fi>
Cc: OCaml List <caml-list@inria.fr>
Subject: Re: [Caml-list] Signature monomorphism in functors
Date: Tue, 18 Jan 2011 23:03:05 +0900 [thread overview]
Message-ID: <F6535A2D-2F8D-484E-8973-8BB06A499F3D@math.nagoya-u.ac.jp> (raw)
In-Reply-To: <20110118121036.GK323@melkinpaasi.cs.helsinki.fi>
On 2011/01/18, at 11:00, Lauri Alanko wrote:
> I guess what I want is "bounded signature polymorphism" of some sort:
>
> module F(A : sig module type S <: S1 module M : S end)
> : S3 with module M = A.M =
> struct
> module M = A.M
> end
>
> module M3B : S3 with module M = M2 =
> F(struct module type S = S2 module M = M2 end)
>
> Alas, there are no signature bounds in ocaml and I cannot offhand
> think of a way to encode them.
You can always encode it by using an abstract module type:
module type S1' = sig type t module type X module X : X end
This way you can put anything you wish in X.
But this is going to be pretty heavy to use...
Alternatively, if you don't need all the functionality of modules,
objects let you do exactly that. A function from objects to objects may
be polymorphic in the available methods.
Jacques Garrigue
next prev parent reply other threads:[~2011-01-18 14:03 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-18 2:00 Lauri Alanko
2011-01-18 10:02 ` rossberg
2011-01-18 10:22 ` rossberg
2011-01-18 12:10 ` Lauri Alanko
2011-01-18 14:03 ` Jacques Garrigue [this message]
2011-01-18 16:41 ` rossberg
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