[Haskell-cafe] what is inverse of mzero and return?

S. Alexander Jacobson alex at alexjacobson.com
Fri Jan 21 18:54:29 EST 2005

I assume there is a standard name for this 

   instance Foo [] where
     foo [] = mzero
     foo (x:_) = return x

   instance Foo (Maybe x) where
     foo Nothing = mzero
     foo Just x = return x


S. Alexander Jacobson tel:917-770-6565 http://alexjacobson.com

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