Optimisation of unpackCString#
ndmitchell at gmail.com
Tue Apr 29 13:39:28 EDT 2008
> > Cons: Makes the simplifier slightly more complex - but I hope not by much!
> And it doesn't work for my case -- I'd really want length as a compile
> time constant.
> Could you elaborate on what kind of rules you think we could write with
> the ability to get the head?
One of my ideas was some RULES that expand:
test x | "neil" `isPrefixOf` x = ...
| "ned" `isPrefixOf` x = ...
And obtains direct pattern-matching code. I have a lazy
continuation-based parsing library which could use this extensively.
See my other ongoing thread on this mailing list for more details of
where this is going.
> The rule I'd like to write is:
> "pack/packAddress" pack (unpackCString addr) = ByteString (length# xs) 0 addr
That requires Proposal 2, so needs to have an API defined -- including
length# and some others. Out of curiosity, how much performance boost
would this give in ByteString?
> That sounds great! Please let's have a chat before you sail in -- I have a good idea where to put this.
Simon: I will email you in a couple of weeks to discuss it.
More information about the Glasgow-haskell-users