From: Markus Mottl <markus.mottl@gmail.com>
To: Yitzhak Mandelbaum <yitzhakm@cs.princeton.edu>
Cc: yoann padioleau <padator@wanadoo.fr>,
Caml-list List <caml-list@inria.fr>
Subject: Re: [Caml-list] typing problem with sexplib and mutually recursive polymorphic types
Date: Wed, 11 Mar 2009 10:44:12 -0400 [thread overview]
Message-ID: <f8560b80903110744v193bd3em905a47b59686eac0@mail.gmail.com> (raw)
In-Reply-To: <6D1EF1C5-3561-4D45-AE32-48F80EC84E58@cs.princeton.edu>
On Wed, Mar 11, 2009 at 10:32, Yitzhak Mandelbaum
<yitzhakm@cs.princeton.edu> wrote:
> While I'm not sure it will help you in this case (because the code is
> generated), I should note that type *inference* for polymorphic recursion is
> undecidable, but type *checking* is not. Moreover, its pretty easy to do in
> OCaml (if a bit clunky).
That's true, but unlike Haskell OCaml doesn't have mandatory types.
This means the user can't force the compiler to start out with
user-provided type declarations. The OCaml compiler will always run
type inference first and only try to unify the result with the
user-provided type declaration, i.e. when it's too late.
Of course, there are workarounds (recursive modules, polymorphic
record fields), but, as you said, they are clunky indeed...
Cheers,
Markus
--
Markus Mottl http://www.ocaml.info markus.mottl@gmail.com
next prev parent reply other threads:[~2009-03-11 14:44 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-11 2:45 Yoann Padioleau
2009-03-11 4:25 ` [Caml-list] " Markus Mottl
2009-03-11 6:11 ` yoann padioleau
2009-03-11 14:20 ` Markus Mottl
2009-03-11 14:32 ` Yitzhak Mandelbaum
2009-03-11 14:44 ` Markus Mottl [this message]
2009-03-11 16:16 ` Damien Doligez
2009-03-11 16:43 ` Markus Mottl
2009-03-11 19:03 ` Till Varoquaux
2009-03-12 1:42 ` Jacques Garrigue
2009-03-11 23:08 ` Yoann Padioleau
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