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

[Simon Marlow]

Richard Kelsall wrote:
> Hello Glasgow-Haskell Users,
> 
> It was suggested to me in this thread in Haskell-Cafe
> 
> http://www.haskell.org/pipermail/haskell-cafe/2008-May/042797.html
> 
> which was a subsidiary of a previous thread
> 
> http://www.haskell.org/pipermail/haskell-cafe/2008-April/042155.html
> 
> 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.)

It's hard to tell what optimisation level your libraries were compiled 
with.  The default setting is -O, but when building binary distributions we 
usually set it explicitly to -O2.  If you got your binary from another 
source, they might have only used -O.

Cheers,
	Simon