
9 Nov
2009
9 Nov
'09
9 p.m.
Excerpts from Ertugrul Soeylemez's message of Mon Nov 09 21:44:44 +0100 2009:
Nicolas Pouillard
wrote: 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') packages.
Either is still not a monad. Have a look at its kind.
OK, right Either is not but (Either e), where e must be in the Error type class. -- Nicolas Pouillard http://nicolaspouillard.fr