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

[S. Alexander Jacobson]

I assume there is a standard name for this 
class/function:

  instance Foo [] where
    foo [] = mzero
    foo (x:_) = return x
  instance Foo (Maybe x) where
    foo Nothing = mzero
    foo Just x = return x
-Alex-


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