From: Jeremy Yallop <yallop@gmail.com>
To: dumitru.potop@inria.fr
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] Bug in the module system of version 3.12.0+beta1
Date: Wed, 21 Jul 2010 15:13:28 +0100 [thread overview]
Message-ID: <AANLkTikvjA641yGQJDFrC-wWOyLRGuudTh=gZjpKiHYj@mail.gmail.com> (raw)
In-Reply-To: <4C46F866.9050900@inria.fr>
On 21 July 2010 14:38, Dumitru Potop-Butucaru
<dumitru.potop_butucaru@inria.fr> wrote:
> module type Abc =
> functor (M:Simple) ->
> sig
> val x : M.t
> end
You're trying to treat Abc as a functor from signatures to signatures
(i.e. as a parameterised signature). In fact, it's something quite
different: it's the *type* of a functor from structures to structures.
You can emulate a parameterised signature using a signature with some
opaque components, which are later specified using substitution.
Here's the "parametrised signature":
module type ABC =
sig
module M : Simple
val x : M.t
end
Here's how to supply a value for M:
module MyModule :
sig
include ABC with module M = IntList
val y : int
end
= ...
In OCaml 3.12 you can use destructive substitution instead, ensuring
that M doesn't appear in the output signature. Note the ':=' in the
line that includes ABC:
module MyModule :
sig
include ABC with module M := IntList
val y : int
end
= ...
next prev parent reply other threads:[~2010-07-21 14:13 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-21 13:38 Dumitru Potop-Butucaru
2010-07-21 14:13 ` Jeremy Yallop [this message]
2010-07-21 15:49 ` [Caml-list] " rossberg
2010-07-21 18:41 ` Dumitru Potop-Butucaru
2010-07-22 2:29 ` Alain Frisch
2010-07-22 6:36 ` Dumitru Potop-Butucaru
2010-07-22 6:18 ` Jacques Garrigue
[not found] ` <4C47E768.4080507@inria.fr>
[not found] ` <9454F06C-C286-4A1F-8A9F-CA3B27F8E3BB@gmail.com>
2010-07-22 7:07 ` Dumitru Potop-Butucaru
2010-07-22 9:37 ` rossberg
2010-07-22 10:44 ` Jacques Garrigue
2010-07-22 12:28 ` Dumitru Potop-Butucaru
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