It's from a retrospective on Haskell: www.cs.nott.ac.uk/~gmh/appsem-slides/peytonjones.ppt There seems to be two arguments against laziness. Firstly, it makes

It's from a retrospective on Haskell: www.cs.nott.ac.uk/~gmh/appsem-slides/peytonjones.ppt There seems to be two arguments against laziness. Firstly, it makes reasoning about performance hard. Secondly, forcing strict evaluation is tricky, maybe harder than it would be to do optional lazy evaluation in a strict language.