Fri, 18 Jan 2002 05:18:07 -0500, Feuer pisze:

Why is mzero in MonadPlus rather than a separate MonadZero class?

It used to be in MonadZero. In Haskell98 these two classes were merged into one. I guess it was to simplify the library and programs using these classes: they are usually defined together and used together. Can you give an example of a useful MonadZero instance without MonadPlus which would be used by some function working on an arbitrary MonadZero? -- __("< Marcin Kowalczyk * qrczak@knm.org.pl http://qrczak.ids.net.pl/ \__/ ^^ QRCZAK