From: Brian Hurt <bhurt@spnz.org>
To: Loup Vaillant <loup.vaillant@gmail.com>
Cc: caml-list@yquem.inria.fr
Subject: Re: [Caml-list] Polymorphic recursion
Date: Wed, 4 Apr 2007 19:36:52 -0400 (EDT) [thread overview]
Message-ID: <Pine.LNX.4.64.0704041934040.5725@localhost> (raw)
In-Reply-To: <6f9f8f4a0704030959l8ebb155g8532e3ee6d31c66d@mail.gmail.com>
On Tue, 3 Apr 2007, Loup Vaillant wrote:
> I was reading Okasaki's book, "Purely functionnal data structures",
> and discovered that ML (and Ocaml) doesn't support non uniforms
> function definitions.
>
> So, even if:
>
> (**)
> type 'a seq = Unit | Seq of ('a * ('a * 'a)seq);;
> (**)
This way lies GADTs, which are a really neat idea, but even the
Haskeller's aren't 100% sure how to implement correctly yet.
In any case, there's a fairly simple work around which does work in the
current type system, which Okasaki describes IIRC. Basically, you just
do:
type 'a tuple = Tuple of 'a tuple * 'a tuple | Leaf of 'a;;
type 'a seq = Unit | Set of 'a tuple * 'a seq;;
which is a bit of a pain, but works.
Brian
next prev parent reply other threads:[~2007-04-04 23:36 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-03 16:59 Loup Vaillant
2007-04-03 17:20 ` [Caml-list] " Jeremy Yallop
2007-04-04 5:27 ` Alain Frisch
2007-04-04 12:54 ` Loup Vaillant
2007-04-03 17:35 ` Till Varoquaux
2007-04-03 20:00 ` brogoff
2007-04-04 1:27 ` skaller
2007-04-04 1:40 ` skaller
2007-04-04 13:49 ` Roland Zumkeller
2007-04-04 15:13 ` Alain Frisch
2007-04-04 15:20 ` Alain Frisch
2007-04-04 16:45 ` Roland Zumkeller
2007-04-04 19:58 ` Alain Frisch
2007-04-04 20:13 ` brogoff
2007-04-05 9:33 ` Roland Zumkeller
2007-04-05 9:54 ` Alain Frisch
2007-04-05 10:07 ` Daniel de Rauglaudre
2007-04-05 9:46 ` Francois Maurel
2007-04-04 15:50 ` Stefan Monnier
2007-04-04 23:36 ` Brian Hurt [this message]
2007-04-05 8:17 ` [Caml-list] " Loup Vaillant
-- strict thread matches above, loose matches on Subject: below --
2008-05-12 21:55 polymorphic recursion Jacques Le Normand
2008-05-12 22:16 ` [Caml-list] " Christophe TROESTLER
2003-08-24 18:01 [Caml-list] Polymorphic recursion Lukasz Stafiniak
2003-08-25 0:30 ` Jacques Garrigue
2003-08-25 0:43 ` Jacques Garrigue
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