úÎ^)(c) Jamaal Malek <mjm540@york.ac.uk> 2014BSD3mjm540@york.ac.uk experimental non-portableNone246BHM\ is a monad transformer that adds backtracking exception handling to its base monad. constructs a  from the base monad. does the opposite of  constructs a  from an  value.         backtracking-exceptions-0.1.0.0!Control.Monad.Except.BacktrackingBExceptTbExceptT runBExceptT hoistEitherbase Data.EitherEitherunwrapBExceptT'unwrapBExceptT$fMonadPlusBExceptT$fAlternativeBExceptT$fPlusBExceptT $fAltBExceptT$fMonadErroreBExceptT$fMonadRWSrwsBExceptT$fMonadWriterwBExceptT$fMonadStatesBExceptT$fMonadReaderrBExceptT$fMonadTransBExceptT$fMonadFreefBExceptT mtl-2.2.1Control.Monad.Error.Class throwErrortransformers-0.4.1.0Control.Monad.Trans.ErrorError catchError MonadErrornoMsgstrMsg