[Haskell-cafe] Fusing foldr's

Isaac Dupree isaacdupree at charter.net
Sat Oct 27 19:16:26 EDT 2007

Josef Svenningsson wrote:
> Less bogus timing:
> avg4: 18.0s
> avgS: 2.2s
> avgP: 17.4s
> OK, so these figures make an even stronger case for my conclusion :-)
> Single traversal can be much faster than multiple traversals *when
> done right*.

Did you use +RTS -N2 on your program (or whatever it is that makes GHC 
actually use multiple threads? or is that not necessary?)  Anyway I 
assume you wouldn't get better than 9.0s, which is still much worse than 


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