Ketil Malde wrote:
Python used to do pretty well here compared to Haskell, with rather efficient hashes and text parsing, although I suspect ByteString IO and other optimizations may have changed that now.
It still does just fine. For typical "munge a file with regexps, lists,
and maps" tasks, Python and Perl remain on par with comparably written
Haskell. This because the scripting-level code acts as a thin layer of
glue around I/O, regexps, lists, and dicts, all of which are written in
native code.
The Haskell regexp libraries actually give us something of a leg down
with respect to Python and Perl. The aggressive use of polymorphism in
the return type of (=~) makes it hard to remember which of the possible
return types gives me what information. Not only did I write a regexp
tutorial to understand the API in the first place, I have to reread it
every time I want to match a regexp.
A suitable solution would be a return type of RegexpMatch a => Maybe a
(to live alongside the existing types, but aiming to become the one
that's easy to remember), with appropriate methods on a, but I don't
have time to write up a patch.