lib/Hcompta/Lib/Consable.hs

   1 {-# LANGUAGE FlexibleContexts #-}
   2 {-# LANGUAGE FlexibleInstances #-}
   3 {-# LANGUAGE MultiParamTypeClasses #-}
   4 {-# OPTIONS_GHC -fno-warn-orphans #-}
   5
   6 module Hcompta.Lib.Consable where
   7
   8 -- import           Data.Functor.Compose (Compose(..))
   9 -- import           Control.Applicative (Const(..))
  10 import           Data.Monoid (Monoid(..))
  11 import           Data.Ord (Ord(..))
  12 import qualified Data.Map.Strict as Map
  13 import           Data.Map.Strict (Map)
  14 import           Prelude (id)
  15
  16 class Consable x m where
  17         mcons :: x -> m -> m
  18
  19 instance Consable x () where
  20         mcons _x = id
  21 instance Consable x [x] where
  22         mcons = (:)
  23
  24 instance (Monoid v, Ord k) => Consable (k, v) (Map k v) where
  25         mcons (k, v) = Map.insertWith mappend k v
  26
  27 {-
  28 instance Monoid (f (g x)) => Monoid ((Compose f g) x) where
  29         mempty = Compose mempty
  30         mappend (Compose x) (Compose y) = Compose (mappend x y)
  31 -}