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You put the blame on me for the bad performance of my code,

I didn't mean to give that impression, sorry. Optimising Haskell code is a delicate art which requires experience and sometimes a deep knowledge of GHC's optimiser. This is a real problem, and we readily accept that.

I just wanted to say that i am aware that i am not (yet) a Haskell pro. I don't really feel blamed. I apologize for the formulation :-) Regards, Andreas Schroeder