[Haskell-cafe] Re: Difference lists and ShowS

[Albert Y. C. Lai]

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.