Stefan O'Rear wrote:
On Sun, Jul 08, 2007 at 12:10:04PM +0100, Andrew Coppin wrote:
(Realistically though. My program takes a [Word8] and turns it into a [Bool] before running a parser over it. The GHC optimiser doesn't really stand a hope in hell of optimising that into a program that reads a machine word into a CPU register and starts playing with bit flips on it...)

Actually, if you're very lucky (fusion is just as hard in Haskell as it
is in real life), it *does*.  It seems to fit nicely into the
stream-fusion framework.

Ooo... really? That's pretty impressive...(!)

Is there a way I can check? ;-) More usefully, can I do stuff to my code to make myself more "lucky"?

(Love the comment about RL BTW!)

PS. Are those zlib libraries actually written in Haskell? Or are they a thin layer on top of a C library?

Yup, they wrap C's zlib.

Thought so. Comparing native Haskell to a heavily optimised C library would surely be just like comparing native Haskell to a compiled C binary...

PPS. Does GHC make use of MMX, SSE, et al?

No (in spirit - the native code generator uses 1-element SSE operations
for floating point because it's easier to optimize than "FPU" code).

Does GHC actually do anything that could usefully use these primitives? (I'm guessing "no"...)

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