On Wed, Dec 30, 2009 at 5:52 PM, Edward Z. Yang <[email protected]> wrote: > Hello all, > > I am currently playing with the new cadre of failure libraries, and I'm > trying to figure out how to use the monadic version of Failure while > also getting the Try typeclass, which appears to be the standardized mechanism > for marshalling values from specific monads into the failure monad. > Unfortunately, it only seems to be defined when I import Control.Failure, > and this module is fairly incompatible with Control.Monad.Failure, as > demonstrated by this GHCI transcript: > > ezy...@javelin:~/Documents/tmr$ ghci > Prelude> :m +Control.Failure > Prelude Control.Failure> :m +Control.Monad.Failure > Prelude Control.Failure Control.Monad.Failure> :t failure > > <interactive>:1:0: > Ambiguous occurrence `failure' > It could refer to either `Control.Failure.failure', imported from > Control.Failure > or `Control.Monad.Failure.failure', imported > from Control.Monad.Failure > > I'm using MTL, which might be the reason why there's all sorts of > unhappiness. :-) > > Cheers, > Edward > _______________________________________________ > Haskell-Cafe mailing list > [email protected] > http://www.haskell.org/mailman/listinfo/haskell-cafe >
Why are you importing both Control.Failure and Control.Monad.Failure when the latter just re-exports the former? Are you using the latest versions of the two packages? Try importing just Control.Monad.Failure.MTL; that provides the MTL failure instances and also re-exports Control.Failure. Alex _______________________________________________ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
