broken Monad Either instance?
Christian.Maeder at dfki.de
Wed Nov 30 13:55:09 CET 2011
Yes, thanks, this works and is worth knowing.
It looks a bit ugly but is shorter than making a new monad.
Prelude Control.Monad.Identity Control.Monad.Error>
runIdentity . runErrorT $ fail "bla" :: Either String ()
Am 30.11.2011 11:39, schrieb Erik Hesselink:
> ErrorT from mtl still has a 'fail' implementation that returns a Left.
More information about the Libraries