Nick wrote:
The question is the following: how big the gap between strict languages with lazy constructs and Haskell? Does the default lazyness have irrefutable advantage over default strictness?
Laziness is needed to achieve true compositionality. This point is elaborated in John Hughes. "Why functional programming matters" http://haskell.org/haskellwiki/Research_papers#Overview I also think that the laziness in Haskell is already so implicit that 90% of the Haskell code written so far will simply break irreparably if you experimentally remove it. By the way, lazy evaluation is strictly more powerful than eager evaluation (in a pure language, that is) with respect to asymptotic complexity: Richard Bird, Geraint Jones and Oege de Moor. "More Haste, Less Speed." http://web.comlab.ox.ac.uk/oucl/work/geraint.jones/morehaste.html Regards, apfelmus