----------------------------------------------------------------------------- -- | -- Module : Control.Monad.Trans -- Copyright : (c) Andy Gill 2001, -- (c) Oregon Graduate Institute of Science and Technology, 2001 -- License : BSD-style (see the file LICENSE) -- -- Maintainer : libraries@haskell.org -- Stability : experimental -- Portability : portable -- -- Classes for monad transformers. -- -- A monad transformer makes new monad out of an existing monad, such -- that computations of the old monad may be embedded in the new one. -- To construct a monad with a desired set of features, one typically -- starts with a base monad, such as @Identity@, @[]@ or 'IO', and -- applies a sequence of monad transformers. -- -- Most monad transformer modules include the special case of applying the -- transformer to @Identity@. For example, @State s@ is an abbreviation -- for @StateT s Identity@. -- -- Each monad transformer also comes with an operation @run@/XXX/ to -- unwrap the transformer, exposing a computation of the inner monad. ----------------------------------------------------------------------------- module Control.Monad.Trans ( module Control.Monad.Trans.Class, module Control.Monad.IO.Class ) where import Control.Monad.IO.Class import Control.Monad.Trans.Class