From: Brian Hurt <bhurt@janestcapital.com>
To: caml-list@yquem.inria.fr
Subject: Re: [Caml-list] best and fastest way to read lines from a file?
Date: Tue, 02 Oct 2007 08:56:34 -0400 [thread overview]
Message-ID: <47024002.2080206@janestcapital.com> (raw)
In-Reply-To: <200710021239.l92CdwZ15641@virtutech.se>
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Mattias Engdegård wrote:
>>let line_count filename =
>> let f = open_in filename in
>> let rec loop count =
>> match (readline f) with
>> | Some(_) -> loop (count+1)
>> | None -> count in
>> loop 0;;
>>
>>
>
>Something like this should be even faster:
>
>exception Done of int
>
>let line_count file =
> let rec loop count =
> let _ =
> try
> input_line f
> with End_of_file -> raise (Done count)
> in
> loop (count + 1)
> in
> try loop 0 with Done x -> x
>
>as it avoids unnecessary consing in the inner loop.
>
>__
>
This should be a FAQ.
let line_count file =
let rec loop count =
let test =
try
let _ = input_line f in
true
with
| Not_found -> false
in
if test then
loop (count + 1)
else
count
in
loop 0
;;
No consing, no unnecessary try/catch, tail recursive.
Brian
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next prev parent reply other threads:[~2007-10-02 12:56 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-01 21:27 YC
2007-10-01 21:55 ` [Caml-list] " Daniel Bünzli
2007-10-01 22:29 ` YC
2007-10-01 21:55 ` Olivier Roussel
2007-10-02 12:39 ` Mattias Engdegård
2007-10-02 12:56 ` Brian Hurt [this message]
2007-10-02 16:15 ` kirillkh
2007-10-02 17:10 ` verlyck, Bruno.Verlyck
2007-10-02 18:02 ` kirillkh
2007-10-02 19:35 ` skaller
2007-10-02 21:05 ` kirillkh
2007-10-02 21:07 ` Jon Harrop
2007-10-02 20:23 ` Olivier Andrieu
2007-10-02 20:49 ` kirillkh
2007-10-02 21:10 ` Jon Harrop
2007-10-02 21:15 ` David Allsopp
2007-10-02 22:23 ` skaller
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