{-
This module is part of Chatty.
Copyleft (c) 2014 Marvin Cohrs
All wrongs reversed. Sharing is an act of love, not crime.
Please share Antisplice with everyone you like.
Chatty is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Chatty is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with Chatty. If not, see .
-}
-- | Provides generic string expansion
module Text.Chatty.Expansion where
import Control.Monad
import Control.Monad.IO.Class
import Control.Monad.Trans.Class
-- | Typeclass for all string-expanding monads.
class Monad e => MonadExpand e where
-- | Expand the given string.
expand :: String -> e String
newtype NullExpanderT m a = NullExpander { runNullExpanderT :: m a }
instance Monad m => Monad (NullExpanderT m) where
return = NullExpander . return
(NullExpander ne) >>= f = NullExpander $ do ne' <- ne; runNullExpanderT (f ne')
instance MonadTrans NullExpanderT where
lift = NullExpander
instance Functor m => Functor (NullExpanderT m) where
fmap f (NullExpander ne) = NullExpander $ fmap f ne
instance MonadIO m => MonadIO (NullExpanderT m) where
liftIO = lift . liftIO
instance Monad m => MonadExpand (NullExpanderT m) where
expand = return
withExpansion :: Monad m => NullExpanderT m a -> m a
withExpansion = runNullExpanderT