On Wed, Feb 22, 2006 at 01:14:41PM +0100, Christian Maeder wrote: > John Meacham wrote: > >f x = ... y ... where > > Just y = Map.lookup x theMap > > > >now if the lookup fails you automatically get an error message pointing > >to the exact line number of the failure. or if the failure message of > >the routine is more important than the source location you can do > > > >f x = ... y ... where > > Identity y = Map.lookup x theMap > > These are potential runtime errors, that may be not so obvious to see in > the source (ie. for user defined types) and even the compiler (ghc) does > not emit a warning.
Indeed, that is the entire point of the construct. ghc definitly should not emit a warning in this case as it is what lazy pattern matching is for. John -- John Meacham - ⑆repetae.net⑆john⑈ _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe