[Haskell-cafe] Either instance of Monad?

Yves Parès limestrael at gmail.com
Sat Feb 26 13:49:52 CET 2011

I tried reinstalling GHC 7.0.1 from scratch, the issue remains...

2011/2/26 Daniel Fischer <daniel.is.fischer at googlemail.com>

> On Saturday 26 February 2011 12:54:02, Yves Parès wrote:
> > When I look at the documentation of Control.Monad.Error [1] or
> > Control.Applicative [2] it is not said that it re-exports
> > Control.Monad.Instances. So maybe this behaviour is normal...
> I don't think so. Instances are automatically propagated, they can't be
> hidden once they're in scope. Functor, Monad, Either and (->) are all
> available in the Prelude, so unless you have NoImplicitPrelude, the
> instances ought to be in scope from any transitive dependency.
> And they are in scope for me when I import Control.Monad.Error or
> Control.Applicative, so something is amiss if they're not in scope for you.
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