[Haskell-cafe] Efficient functional idiom for histogram

Ketil Malde ketil at malde.org
Sat Aug 1 13:36:32 EDT 2009

Paul Moore <p.f.moore at gmail.com> writes:

> What am I doing wrong here? I'd have expected compiled Haskell to be
> faster than interpreted Python, so obviously my approach is wrong.

Two things from my experience: Python associative arrays are fast, and
Haskell random numbers are slow.  So by building a map from random
numbers, you are likely doing a fairly pessimal comparison.  Did you
profile to see where the time is spent? 

> I'm expecting the answer to be that I've got unnecessary laziness

IME, laziness usually affects space, but not so much time
performance.  Although 'insertWith (+)' looks like it would build
unevaluated thunks for the sums.

If I haven't seen further, it is by standing in the footprints of giants

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