From: Alex Baretta <alex@barettadeit.com>
To: Ocaml <caml-list@inria.fr>
Subject: Problem with local modules
Date: Mon, 18 Apr 2005 16:02:07 +0200 [thread overview]
Message-ID: <4263BDDF.3050903@barettadeit.com> (raw)
I have written a list-of-sorted-lists merging function which takes
advantage of a functional heap module by Jean-Christophe Filliatre. I
would like to avoid the functorial style of the heap library by using
local modules; however, the type system does not allow me to bind the
"type t" of the local parameter module to a type variable, which is
bound in the containing expression.
This is what I would like to have:
let rev_merge_list_rev_filter_append
(cmp : 'a -> 'a -> int)
(p : 'a -> bool)
(ll : 'a list list)
(accu : 'a list)
=
let module Ordered = struct
type t = Obj.t * (Obj.t list)
let compare (x,tlx) (y,tly) = cmp ((Obj.obj x):'a) ((Obj.obj y):'a)
end in
let module Heap = Heap.Functional (Ordered)
in
...
This is what I had to write.
let rev_merge_list_rev_filter_append
(cmp : 'a -> 'a -> int)
(p : 'a -> bool)
(ll : 'a list list)
(accu : 'a list)
=
let module Ordered = struct
type t = Obj.t * (Obj.t list)
let compare (x,tlx) (y,tly) = cmp ((Obj.obj x):'a) ((Obj.obj y):'a)
end in
let module Heap = Heap.Functional (Ordered)
in
...
Is this a limitation of the type theory or of the type checker? Is there
any other way out than using the Obj module?
Alex
--
*********************************************************************
http://www.barettadeit.com/
Baretta DE&IT
A division of Baretta SRL
tel. +39 02 370 111 55
fax. +39 02 370 111 54
Our technology:
The Application System/Xcaml (AS/Xcaml)
<http://www.asxcaml.org/>
The FreerP Project
<http://www.freerp.org/>
reply other threads:[~2005-04-18 14:02 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4263BDDF.3050903@barettadeit.com \
--to=alex@barettadeit.com \
--cc=caml-list@inria.fr \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).