From: Pierre Weis <pierre.weis@inria.fr>
To: sebastien.furic@tni-valiosys.com (sebastien FURIC)
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] Question
Date: Wed, 10 Dec 2003 11:27:59 +0100 (MET) [thread overview]
Message-ID: <200312101027.LAA20728@pauillac.inria.fr> (raw)
In-Reply-To: <3FCB610E.932B363B@tni.fr> from sebastien FURIC at "Dec 1, 103 04:41:02 pm"
[...]
> I was expecting "when" to be right distributive over "|". I find
> OCaml's behaviour not very intuitive in such a situation.
[...]
The when construct introduces a guard to a pattern matching
clause. This means that a when construct is global to the entire
pattern of the clause it appears in; it means in particular that no
when construct can be nested into a pattern and the question of its
distributivity wrt any other construct is pointless.
> Is there a good reason for this?
Yes: simplicity, complexity invariants preservation for runtime
pattern analysis decisions even in the presence of when clauses,
easier understanding of the compiler warnings, simplicity and
well-definedness semantics (in particular the desired invariance wrt
the order of evaluation).
> Cheers,
>
> Sébastien.
Best regards,
Pierre Weis
INRIA, Projet Cristal, Pierre.Weis@inria.fr, http://pauillac.inria.fr/~weis/
-------------------
To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr
Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/
Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
next prev parent reply other threads:[~2003-12-10 10:28 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-12-01 15:41 sebastien FURIC
2003-12-01 17:48 ` Remi Vanicat
2003-12-01 18:04 ` sebastien FURIC
2003-12-03 14:02 ` Damien Doligez
2003-12-10 10:27 ` Pierre Weis [this message]
2003-12-10 15:53 ` skaller
2003-12-11 9:52 ` Luc Maranget
2003-12-11 14:20 ` skaller
2003-12-11 16:56 ` Luc Maranget
2005-05-23 6:54 Question dsingh01
2005-05-23 7:40 ` [Caml-list] Question Remi Vanicat
2005-05-23 12:21 ` Jacques Carette
2005-06-08 10:06 question dsingh01
2005-06-08 15:13 ` [Caml-list] question Damien Bobillot
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=200312101027.LAA20728@pauillac.inria.fr \
--to=pierre.weis@inria.fr \
--cc=caml-list@inria.fr \
--cc=sebastien.furic@tni-valiosys.com \
/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