[Haskell-beginners] Either Monadic Trouble
nicolas.pouillard at gmail.com
Mon Nov 9 06:40:38 EST 2009
Excerpts from Henk-Jan van Tuyl's message of Mon Nov 09 11:10:07 +0100 2009:
> Either is not a monad, you can check this by typing
> :i Either
> in GHCi; you will not see a line like
> instance Monad Either
> in the result. Compare this to
> :i Maybe
In fact the Either Monad instance is defined in the 'transformers' (or 'mtl')
However for this reason among others you may want to use the 'attempt'
package instead of Either.
More information about the Beginners