module Symantic.Compta.Input.Chart where

import Control.Applicative (Applicative(..))
import Control.Monad (Monad(..))
import Data.Foldable (foldr)
import Data.Functor (Functor)
import Data.Monoid (Monoid(..))
import Data.Ord (Ord(..))
import Data.Semigroup (Semigroup(..))
import Prelude (error)
import qualified Control.Monad.Trans.Writer as MT
import qualified GHC.Exts as GHC

import Symantic.Compta.Lang.Rebindable
import Symantic.Compta.Lang
import Symantic.Compta.Calc.Chart

-- * Type 'ChartM'
-- | A 'Monad' to construct a 'Chart'.
newtype ChartM k v m a = ChartM { unChartM ::
  MT.WriterT (v, Chart k v) m a
  } deriving newtype (Functor, Applicative, Monad)

runChartM :: Monad m => ChartM k v m a -> m (Chart k v)
runChartM chM = do
  (_a, (_v, ch)) <- MT.runWriterT (unChartM chM)
  return ch

instance (Ord k, Monoid v, Monad m) => Semigroup (ChartM k v m a) where
  (<>) = (Control.Monad.>>)
instance (Ord k, Monoid v, Monad m, Monoid a) => Monoid (ChartM k v m a) where
  mempty = return mempty
instance
  ( Ord k
  , Monoid v
  , Monad m
  , Monoid a
  ) => GHC.IsList (ChartM k v m a) where
  type Item (ChartM k v m a) = ChartM k v m a
  fromList = mconcat
  fromListN _n = mconcat
  toList = return