From: Xavier Leroy <xavier.leroy@inria.fr>
To: caml-list@inria.fr
Subject: Re: [Caml-list] Guards vs. conditionals
Date: Thu, 2 Jan 2003 10:54:22 +0100 [thread overview]
Message-ID: <20030102105422.I24166@pauillac.inria.fr> (raw)
In-Reply-To: <20021226070651.GB1071@swordfish>; from mgushee@havenrock.com on Thu, Dec 26, 2002 at 12:06:52AM -0700
> I'm just curious about something. I've been noticing that in many cases
> (if not always) a pattern match with guard expressions in OCaml is
> equivalent to a conditional statement.
Not always strictly equivalent. Consider
match x with hd::tl when hd <> 0 -> <expr1>
| _ -> <expr2>
Without "when", you'd need to duplicate <expr2>:
match x with hd::tl -> if hd <> 0 then <expr1> else <expr2>
| _ -> <expr2>
> So, my question is, is there any objective reason to prefer the
> pattern-match version over the conditional, or vice versa? Or is it just
> a matter of coding style?
It's just a question of style. Personally, I'd recommend using "when"
in cases where "real" pattern-matching is involved, as in the example
above, and cascades of "if...then...else..." in cases where it doesn't
cause duplication of code. But you can opt for a different style.
- Xavier Leroy
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next prev parent reply other threads:[~2003-01-02 9:54 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-12-26 7:06 Matt Gushee
2002-12-26 9:13 ` Sven Luther
2002-12-26 16:36 ` Pierre Weis
2003-01-02 9:54 ` Xavier Leroy [this message]
[not found] <D4DBD8568F05D511A1C20002A55C008C11AC0404@uswaumsx03medge.med.ge.com>
2002-12-27 7:37 ` Matt Gushee
2002-12-27 9:15 ` Luc Maranget
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