[Haskell-cafe] Re: Is Haskell capable of matching C in string processing performance?

[John Lato]

> From: Heinrich Apfelmus <apfelmus at quantentunnel.de>
> Don Stewart wrote:
>> jmillikin:
>>> Here's the fastest Haskell version I could come up with. It discards
>>> all error handling, validation, and correctness in the name of
>>> performance, but still can't get anywhere near C:
>>> http://hpaste.org/fastcgi/hpaste.fcgi/view?id=16423
>>
>> Thanks for posting the code.
>>
>> You're not using bytestrings??
>>
>> They were invented to deal with the problem of [Char] being a poor
>> structure for large scale string processing, and you should have no
>> problem getting C-like string performance.
>>
>>     http://www.cse.unsw.edu.au/~dons/papers/CSL06.html
>
> In my limited experience, ByteStrings are great for reading data, but
> not that good for writing data that is being generated on the fly. For
> writing, good old difference lists or the  Builder  monoid / Put monad
> from Data.Binary seem to be best.
>

If find that this is particularly true if you don't know the length of
data to write in advance because it involves lots of new allocations
and copying.  Using Builder/Put is definitely a better approach.

Out of curiousity, has anyone ever tried implementing a
LinkedListString in C to check what its performance would be?  I
expect it would be pretty poor compared to standard strings.

Cheers,
John