From: John Harrison <John.Harrison@cl.cam.ac.uk>
To: caml-list@inria.fr
Cc: John.Harrison@cl.cam.ac.uk
Subject: Re: Functional composition operator?
Date: Tue, 08 Dec 1998 21:52:54 +0000 [thread overview]
Message-ID: <E0znV41-00070g-00@heaton.cl.cam.ac.uk> (raw)
In-Reply-To: Your message of "Tue, 08 Dec 1998 18:02:21 +0100." <199812081702.SAA29130@pauillac.inria.fr>
Pierre Weis writes:
| In fact we discourage the usage of functional composition as a general
| programming tool
A very bad idea, in my opinion.
| -- it only save a few characters in programs
| (Compare
| let h = f o g
| with
| let h x = f (g x);;)
| -- it breaks the polymorphism
| (if defined as
| let h = f o g
| h is not generalized, since its definition is a function
| application, whereas inline expansion of functional composition
| let h x = f (g x)
| being the definition of a function is properly generalized.)
These alternatives are not semantically equivalent. If f and g are
complicated expressions that can be further evaluated, it is often
highly undesirable to perform the evaluation every time h is called,
which is what "let h x = f(g x)" entails.
John.
next prev parent reply other threads:[~1998-12-09 9:13 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-12-08 5:23 John Whitley
1998-12-08 17:02 ` Pierre Weis
1998-12-08 21:52 ` John Harrison [this message]
1998-12-09 10:58 ` Pierre Weis
1998-12-09 17:17 ` John Harrison
1998-12-11 13:57 ` Pierre Weis
1998-12-08 18:08 Andrew Kay
1998-12-08 20:32 ` John Prevost
1998-12-09 16:17 ` Anton Moscal
1998-12-08 19:51 Don Syme
1998-12-08 20:09 Don Syme
1998-12-09 12:00 Don Syme
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