Re: [Haskell-cafe] Questions about the Functor class and it's use in "Data types à la carte"

Am I correct in assuming that if my program doesn't contain seq then I can reason using eta reduction?

You may be well aware of this, but the wiki page on the correctness of short cut fusion (http://haskell.org/haskellwiki/ Correctness_of_short_cut_fusion) really helped me to get at least a basic intuition for how to reason around the oddities introduced by seq. Some of the papers linked were very handy as well, although I'll confess to only partially understanding them. --s