Re: [Haskell-cafe] Re: Difference lists and ShowS

apfelmus wrote:

I don't know a formalism for easy reasoning about time in a lazy language. Anyone any pointers? Note that the problem is already present for difference lists in strict languages.

http://homepages.inf.ed.ac.uk/wadler/topics/strictness-analysis.html especially "strictness analysis aids time analysis". Much CPO math is involved, but I view it as: a function gives you output; if you know how much of the output you use, you can deduce how much work the function goes through.