[darcs-users] Regular Expression libraries and linker errors

Jason Dagit dagit at codersbase.com
Tue Oct 6 02:54:16 UTC 2009


On Mon, Oct 5, 2009 at 6:25 PM, Trent W. Buck <twb at cybersource.com.au>wrote:

> Ben Franksen <benjamin.franksen at bessy.de> writes:
>
> > Jason Dagit wrote:
> >> It's possible that regex-pcre gives better performance than regex-posix
> >
> > I made some tests using the new criterion package (excellent for stuff
> > like that) and found regex-pcre to be faster by a factor of 3 to 9,
> > depending on regex and test string. I did not test it with darcs, but
> > I took some random regexes from the standard boring file and a random
> > file with a long path.
>
> Does the default ERE matcher use the OS's regexp implementation, or is
> it purely done in Haskell?  In the former case, the OS and OS version
> might be significant -- e.g. AIX 4 might have much slower EREs than a
> recent GNU/Linux.
>

I don't think regex-posix is the OS's implementation.  Or if it is, then I'm
not sure what magic is done to provide that implementation on windows.
Perhaps there is a bundled source version which is used if the OS's doesn't
provide an implementation?  I guess this makes performance testing
worthwhile on windows.

Ben, could you make the source for your test publicly available (why
duplicate effort, if we don't have to).  Maybe someone will volunteer to
crunch some numbers on windows.

Jason
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