lib/Hcompta/Amount.hs

   1 module Hcompta.Amount where
   2
   3 import Data.Data (Data)
   4 import Data.Function ((.))
   5 import Data.Map.Strict (Map)
   6 import qualified Data.MonoTraversable as MT
   7 import Data.Ord (Ord(..), Ordering)
   8 import Data.Tuple (fst, snd)
   9 import Data.Proxy (Proxy(..))
  10
  11 import Hcompta.Quantity
  12 import Hcompta.Unit (Unit(..))
  13 import Hcompta.Has
  14
  15 class
  16  ( HasI Quantity a
  17  , HasI Unit a
  18  ) => Amount a
  19
  20 class Amount (MT.Element as) => Amounts as
  21
  22 {-
  23 -- * Class 'Amount'
  24 class
  25  ( Data a
  26  -- , Eq   (Amount_Quantity a)
  27  , Zero (Amount_Quantity a)
  28  , Unit (Amount_Unit     a)
  29  ) =>  Amount          a where
  30         type Amount_Quantity a
  31         type Amount_Unit     a
  32         amount_quantity :: a -> Amount_Quantity a
  33         amount_unit     :: a -> Amount_Unit     a
  34 instance -- (unit, qty)
  35  ( Zero qty
  36  , Unit unit
  37  ) => Amount (unit, qty) where
  38         type Amount_Quantity (unit, qty) = qty
  39         type Amount_Unit     (unit, qty) = unit
  40         amount_quantity = snd
  41         amount_unit     = fst
  42 amount_sign ::
  43  ( Amount a
  44  , Ord (Amount_Quantity a)
  45  ) => a -> Ordering
  46 amount_sign = quantity_sign . amount_quantity
  47
  48 -- * Class 'Amounts'
  49 class Amount (Amounts_Amount amts) => Amounts amts where
  50         type Amounts_Amount amts
  51 instance
  52  ( Zero qty
  53  , Unit unit
  54  ) => Amounts (Map unit qty) where
  55         type Amounts_Amount (Map unit qty) = (unit, qty)
  56 -}