[Haskell-cafe] C-like Haskell

Duncan Coutts duncan.coutts at worc.ox.ac.uk
Wed Jan 28 20:06:17 EST 2009

On Wed, 2009-01-28 at 16:42 -0800, drblanco wrote:

> I do already have the number I wanted, but was wondering how this could be
> made faster, or even why it's so slow.  This is all on GHC 6.8.3 under OS X
> Intel, using ghc -O2.

I'm not exactly sure what's different, but for me it works pretty well.
I put back in the Int64 type signature.

> For comparison, the C code below runs in <1 second.

You've got a faster machine than me :-)

I compiled both the Haskell and C versions to standalone executables
with ghc/gcc -O2 and ran them with time.

C version:
$ time ./circ 

real	0m2.430s
user	0m2.428s
sys	0m0.000s

Haskell version:
time ./circ2

real	0m2.753s
user	0m2.756s
sys	0m0.000s

Not too bad I'd say! :-)

I was using ghc-6.10 for this test. It would appear that ghc-6.8 is a
bit slower, I get:


real	0m5.767s
user	0m5.768s
sys	0m0.000s

Now the other difference is that I'm using a 64bit machine so perhaps
ghc just produces terrible code for Int64 on 32bit machines.


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