On Thu, Jul 8, 2010 at 3:45 PM, Daniel Fischer <daniel.is.fisc...@web.de> wrote: > > Well, I made the suggestion of emitting a warning on instance declarations > without method definitions. That would be comparatively easy to implement > (even with an additional check to only emit the warning if the class > defines any methods) and catch many (if not most) cases. >
Unfortunately, it would catch some perfectly valid cases, see the list of instances for flat datatypes here: http://hackage.haskell.org/packages/archive/deepseq/1.1.0.0/doc/html/src/Control-DeepSeq.html This demonstrates that there is at least one (admittedly probably not much more than one) case where a class with methods would have a default implementation that was total and valid in some cases. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe