From: Keith Wansbrough <Keith.Wansbrough@cl.cam.ac.uk>
To: Daniel Andor <da209@cam.ac.uk>
Cc: Ocaml <caml-list@inria.fr>
Subject: Re: [Caml-list] looping recursion
Date: Thu, 29 Jul 2004 10:25:57 +0100 [thread overview]
Message-ID: <E1Bq7Aj-0001vn-00@mta1.cl.cam.ac.uk> (raw)
In-Reply-To: Your message of "Thu, 29 Jul 2004 10:13:12 BST." <200407291013.12467.da209@cam.ac.uk>
> Lemme try it out (10^6 elements):
>
> ocamlc:
> rev rev_map version:
> 2 WALL ( 1.19 usr + 0.02 sys = 1.21 CPU)
> vanilla map:
> 7 WALL ( 6.50 usr + 0.09 sys = 6.59 CPU)
>
> ocamlopt:
> rev rev_map version:
> 1 WALL ( 0.81 usr + 0.03 sys = 0.84 CPU)
> vanilla map:
> 2 WALL ( 2.45 usr + 0.02 sys = 2.47 CPU)
OK, so why is List.map in the OCaml standard library implemented the
vanilla way rather than the rev rev_map way? If it's such a big win,
it seems foolish to have a broken implementation for such a crucial
function.
(BTW, if you want efficient (and pure) mapping and filtering over long
streams, you should consider using lazy lists. A good compiler (like
GHC) will do the deforestation optimisation, so the list is never even
allocated[1].)
[1] unless you make use of persistence, of course.
--KW 8-)
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next prev parent reply other threads:[~2004-07-29 9:26 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-07-27 23:43 briand
2004-07-28 0:27 ` John Prevost
2004-07-28 0:38 ` John Prevost
2004-07-28 1:17 ` skaller
2004-07-28 1:05 ` briand
2004-07-28 1:43 ` Brian Hurt
2004-07-28 2:49 ` briand
2004-07-28 3:12 ` Brian Hurt
2004-07-28 3:20 ` Brian Hurt
2004-07-28 5:54 ` brogoff
2004-07-28 7:22 ` Alex Baretta
2004-07-28 16:38 ` brogoff
2004-07-28 19:40 ` Jon Harrop
2004-07-28 20:18 ` Brandon J. Van Every
2004-07-29 6:01 ` Alex Baretta
2004-07-28 21:22 ` brogoff
2004-07-29 9:13 ` Daniel Andor
2004-07-29 9:25 ` Keith Wansbrough [this message]
2004-07-29 9:41 ` Nicolas Cannasse
2004-07-29 9:57 ` Xavier Leroy
2004-07-29 10:44 ` Daniel Andor
2004-07-29 12:56 ` brogoff
2004-07-29 10:11 ` skaller
2004-07-29 12:41 ` brogoff
2004-07-29 6:28 ` Alex Baretta
2004-07-29 14:58 ` brogoff
2004-07-29 16:12 ` Brian Hurt
2004-07-29 17:49 ` james woodyatt
2004-07-29 19:25 ` Brian Hurt
2004-07-29 20:01 ` brogoff
2004-07-30 4:42 ` james woodyatt
2004-07-29 17:44 ` james woodyatt
2004-07-29 23:12 ` skaller
2004-07-29 22:42 ` Alex Baretta
2004-07-30 2:38 ` Corey O'Connor
[not found] ` <200407300136.14042.jon@jdh30.plus.com>
2004-07-30 12:45 ` Alex Baretta
2004-07-30 17:07 ` brogoff
2004-07-30 18:25 ` [Caml-list] kaplan-okasaki-tarjan deque (was "looping recursion") james woodyatt
2004-07-30 21:20 ` brogoff
2004-07-31 5:37 ` james woodyatt
2004-07-28 7:27 ` [Caml-list] looping recursion skaller
2004-07-28 14:36 ` Brian Hurt
2004-07-28 22:05 ` skaller
2004-07-28 0:37 ` skaller
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