content: -- ghc-mod: Happy Haskell Hacking
  -- Copyright (C) 2015,2016  Daniel Gröber <dxld ÄT darkboxed DOT org>
  --
  -- This program 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.
  --
  -- This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
  
  {-# LANGUAGE GeneralizedNewtypeDeriving, StandaloneDeriving #-}
  {-# LANGUAGE FlexibleInstances, UndecidableInstances #-}
  
  module GhcMod.Monad.Log where
  
  import GhcMod.Types
  import GhcMod.Monad.Newtypes
  
  import Control.Monad
  import Control.Monad.Trans.Journal (JournalT)
  import Control.Monad.Reader (ReaderT(..))
  import Control.Monad.State.Strict (StateT(..))
  import Control.Monad.Error (Error, ErrorT(..))
  import Control.Monad.Trans.Maybe (MaybeT(..))
  import Control.Monad.Journal.Class (MonadJournal(..))
  import Control.Monad.Trans.Class (MonadTrans(..))
  import Prelude
  
  class Monad m => GmLog m where
      gmlJournal :: GhcModLog -> m ()
      gmlHistory :: m GhcModLog
      gmlClear   :: m ()
  
  instance Monad m => GmLog (JournalT GhcModLog m) where
      gmlJournal = journal
      gmlHistory = history
      gmlClear   = clear
  
  instance Monad m => GmLog (GmT m) where
      gmlJournal = GmT . lift . lift . journal
      gmlHistory = GmT $ lift $ lift history
      gmlClear   = GmT $ lift $ lift clear
  
  instance (Monad m, GmLog m) => GmLog (ReaderT r m) where
      gmlJournal = lift . gmlJournal
      gmlHistory = lift gmlHistory
      gmlClear = lift  gmlClear
  
  instance (Monad m, GmLog m) => GmLog (StateT s m) where
      gmlJournal = lift . gmlJournal
      gmlHistory = lift gmlHistory
      gmlClear = lift gmlClear
  
  instance (Monad m, GmLog m, Error e) => GmLog (ErrorT e m) where
      gmlJournal = lift . gmlJournal
      gmlHistory = lift gmlHistory
      gmlClear = lift gmlClear
  
  instance (Monad m, GmLog m) => GmLog (MaybeT m) where
      gmlJournal = lift . gmlJournal
      gmlHistory = lift gmlHistory
      gmlClear = lift gmlClear
  
  deriving instance GmLog m => GmLog (GmOutT m)
  deriving instance (Monad m, GmLog (GhcModT m)) => GmLog (GmlT m)
  