Hi David, thank you! This is really useful information!
I think it's the let floating (out) together with common subexpression elimination:
ghc --make -O2 -no-recomp -fno-cse -o curry-no-cse curry.hs [1 of 1] Compiling Main ( curry.hs, curry.o ) Linking curry-no-cse ... ghc --make -O2 -no-recomp -fno-full-laziness -o curry-no-fll curry.hs [1 of 1] Compiling Main ( curry.hs, curry.o ) Linking curry-no-fll ... ghc --make -O2 -no-recomp -fno-full-laziness -fno-cse -o curry-no-cse-no-fll curry.hs [1 of 1] Compiling Main ( curry.hs, curry.o ) Linking curry-no-cse-no-fll ... ./curry-no-cse 3 possibilities: [True,False] 2 possibilities: [True,False] ./curry-no-fll 3 possibilities: [True,False] 2 possibilities: [True,False] ./curry-no-cse-no-fll 3 possibilities: [True,True,False] 2 possibilities: [True,False]
I will try this on large scale Curry programs. I hope the remaining optimizations will still do some good. Do you think that there is a way to be more selective? I mean to select those parts of the program which can and which cannot be optimized?
ps.: Maybe it is interesting to look at HasFuse [1] (somewhat outdated), but it exactly forbids both transformations
[1] http://www.ki.informatik.uni-frankfurt.de/research/diamond/hasfuse/
Yes, that looks interesting, too. Are there plans to update it with the ghc? Thanks for your hints! Bernd