On Thu, Aug 20, 2009 at 1:02 PM, Ketil Malde<ke...@malde.org> wrote: > David Leimbach <leim...@gmail.com> writes: > >> I'm pretty certain that forcing a pattern match via case is what disallows >> the laziness to get out of hand. The case statement, when evaluated, must >> choose a matched pattern branch, even if it's the only possibility, which >> ends up boiling down to "seq" anyway doesn't it? > > Prelude> case undefined of x -> () > () > > So I think you are incorrect: the 'undefined' here isn't evaluated by > the case. >
It's doing a case on a pattern match that forces evaluation. Try: > case undefined of (x:xs) -> () Antoine _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
