30 Nov
2011
30 Nov
'11
7:55 a.m.
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 () Left "bla" C. Am 30.11.2011 11:39, schrieb Erik Hesselink:
ErrorT from mtl still has a 'fail' implementation that returns a Left.
Erik