[Haskell-cafe] Much faster complex monad stack based on CPS state
nicu.ionita at acons.at
Tue Sep 27 01:07:00 CEST 2011
Starting from this emails
(http://web.archiveorange.com/archive/v/nDNOvSM4JT3GJRSjOm9P) I could
refactor my code (a UCI chess engine, with complex functions, in which
the search has a complex monad stack) to run twice as fast as with even
some hand unroled state transformer! So from 23-24 kilo nodes per second
it does now 45 to 50 kNps! And it looks like there is still some
improvement room (I have to play a little bit with strictness
annotations and so on).
(Previously I tried specializations, then I removed a lot of
polimorphism, but nothing helped, it was like hitting a wall.)
Even more amazingly is that I could program it although I cannot really
understand the Cont & ContT, but just taking the code example from Ryan
Ingram (newtype ContState r s a = ...) and looking a bit at the code
from ContT (from the transformers library), and after fixing some
compilation errors, it worked and was so fast.
I wonder why the transformers library does not use this kind of state
monad definition. Or does it, and what I got is just because of the
unrolling? Are there monad (transformers) libraries which are faster? I
saw the library kan-extensions but I did not understand (yet) how to use it.
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