From: Andres Varon <avaron@gmail.com>
To: Jacques Garrigue <garrigue@math.nagoya-u.ac.jp>
Cc: caml-list@yquem.inria.fr
Subject: Re: [Caml-list] Polymorphic variants question
Date: Sat, 2 Sep 2006 21:22:55 -0400 [thread overview]
Message-ID: <C90730C4-FF32-4C53-A177-7385E56BB4F6@gmail.com> (raw)
In-Reply-To: <20060902.201646.110439764.garrigue@math.nagoya-u.ac.jp>
On Sep 2, 2006, at 7:16 AM, Jacques Garrigue wrote:
> Just that the concrete type is much simpler.
> The abstract type does not work directly, as you need a way to ensure
> that B.t and C.t are compatible. Otherwise, one could write
>
> module D = A(struct type t = [ `A of int] ... end)
> (struct type t = [ `A of string] ... end)
>
> which is clearly incorrect.
I use a more restricted version of polymorphic variants to ensure
that two functions that are being composed through a match in the
style of the question do not share a tag (and so one function will
not override the expected behavior of the second one), even if the
tags are fully compatible; being this the case, your example cannot
occur.
I am not an expert in programming languages, and I cannot see - in
this restricted case - a reason why that functor could still be
problematic. Is there some?
Thanks!
Andres
next prev parent reply other threads:[~2006-09-03 1:22 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-09-01 17:31 David Allsopp
2006-09-01 18:33 ` Chris King
2006-09-01 19:00 ` [Caml-list] " skaller
2006-09-01 19:57 ` David Allsopp
2006-09-01 20:40 ` Jacques Carette
2006-09-01 18:40 ` [Caml-list] " Olivier Andrieu
2006-09-01 19:26 ` Jon Harrop
2006-09-01 19:29 ` skaller
2006-09-01 20:49 ` Andres Varon
2006-09-02 11:16 ` Jacques Garrigue
2006-09-03 1:22 ` Andres Varon [this message]
2006-09-03 9:08 ` Jacques Garrigue
2006-09-03 15:00 ` Andres Varon
2006-09-03 23:18 ` Jacques Garrigue
2006-09-03 0:48 ` [Caml-list] Polymorphic variants problem skaller
2006-09-03 1:12 ` Andres Varon
-- strict thread matches above, loose matches on Subject: below --
2001-07-20 1:05 [Caml-list] polymorphic variants question John Max Skaller
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