How do I check the optimisation level of the built-in splitAt? Is something other than -O2 giving me my speed increase?

Richard Kelsall r.kelsall at
Wed May 14 10:08:51 EDT 2008

Hello Glasgow-Haskell Users,

It was suggested to me in this thread in Haskell-Cafe

which was a subsidiary of a previous thread

that there might be some reason other than the -O2 optimisation level
I applied to my version of splitAt that was making my program run about
30% faster than when I used the built-in splitAt.

Can somebody tell me how to check what the -O level is for the built-in
splitAt? Or alternatively tell me what the optimisation level is for
the libraries.

(Sorry I'm not sure of the right terminology for these built-in /
library / Prelude things.)


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