Hi, I may be wrong here, but I don't belive it's just let-patterns that have this property. I.e. what's the difference between... (Just x) = _|_ f = x vs. f = let (Just x) = _|_ in x vs. f = x where (Just x) = _|_ I believe Haskell uses Normal Order Reduction in all these cases. Why is it just let-patterns? Can you give an example? Thanks, Chris. On Wed, 27 Aug 2008, Brandon S. Allbery KF8NH wrote:
On 2008 Aug 27, at 14:23, Maurí cio wrote:
What does '~' mean in Haskell? I read in haskell.org/haskellwiki/Keywords that “(...) Matching the pattern ~pat against a value always suceeds, and matching will only diverge when one of the variables bound in the pattern is used.” Isn't that true for any variable, due to lazyness?
Only in let-patterns; others, including case expressions and top level definitions, are strict (which is in fact the normal way to force a value).