{- 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 <http://www.gnu.org/licenses/>. -} module Text.Chatty.Expansion.History where import Prelude hiding (id,(.)) import Control.Arrow import Control.Category (id,(.)) import Control.Monad import Control.Monad.IO.Class import Control.Monad.Trans.Class import Text.Chatty.Expansion newtype HistoryT m a = History { runHistoryT :: [String] -> m (a,[String]) } instance Monad m => Monad (HistoryT m) where return a = History $ \s -> return (a,s) (History h) >>= f = History $ \s -> do (a,s') <- h s; runHistoryT (f a) s' instance MonadTrans HistoryT where lift m = History $ \s -> do a <- m; return (a,s) instance MonadIO m => MonadIO (HistoryT m) where liftIO = lift . liftIO instance Monad m => Functor (HistoryT m) where fmap f a = History $ \s -> do (a',s') <- runHistoryT a s; return (f a',s') class Monad he => HistoryEnv he where mcounth :: he Int mgeth :: Int -> he String mputh :: String -> he () instance Monad m => HistoryEnv (HistoryT m) where mcounth = History $ runKleisli (arr length &&& id) mgeth i | i <= 0 = let j = -i in History $ runKleisli (arr (!!j) &&& id) | otherwise = History . runKleisli $ arr ((!!i).reverse &&& id) mputh s = History . runKleisli $ arr (const () &&& (s:)) expandHist :: HistoryEnv h => String -> h String expandHist [] = return [] expandHist ('!':ss) = let (nm,rm) = (takeWhile isNum &&& dropWhile isNum) ss isNum a = elem a ['0'..'9'] || (a=='-') in case nm of [] -> do ss' <- expandHist ss return ('!':ss') _ -> do hs <- expandHist rm h <- mgeth $ read nm return (h++hs) expandHist (s:ss) = do ss' <- expandHist ss; return (s:ss') instance MonadExpand m => MonadExpand (HistoryT m) where expand = lift . expand <=< expandHist withHistory :: Monad m => HistoryT m a -> m a withHistory = liftM fst . flip runHistoryT []