úÎ]öNone We use the $ to convert between similar classes  like MTL''s  and GHC''s .               ghc-mtl-1.0.1.2Control.Monad.Ghc ghc-7.6.3GhcMonad setSession getSessionGhcTGhcrunGhcrunGhcT MTLAdaptertransformers-0.3.0.0Control.Monad.IO.ClassMonadIOunWrapunGhcT$fExceptionMonadMTLAdapter$fMonadIOMTLAdapter$fGhcMonadGhcT$fExceptionMonadGhcT$fMonadCatchIOGhcT $fMonadIOGhcT$fMonadIOGhcT0$fMonadTransGhcT$fMonadCatchIOGhc $fMonadIOGhcControl.Monad.Trans.Classlift MonadTransliftIO