slackbuilds/haskell/haskell-fail/README

This package contains the Control.Monad.Fail module providing the
MonadFail class that became available in base-4.9.0.0 for older base
package versions.

This package turns into an empty package when used with GHC versions
which already provide the Control.Monad.Fail module to make way for
GHC's own Control.Monad.Fail module.

After uninstalling, run this command to unregister the package from
the ghc package database:   ghc-pkg recache