{-# LANGUAGE ConstraintKinds #-}
module Hcompta.Data where

import Data.Tuple (fst, snd)

-- * Class 'Has'
type Has ty a = (Get ty a, Set ty a)

-- ** Class 'Get'
class Get ty a where
	get :: a -> ty
instance Get a (a, b) where get = fst
instance Get b (a, b) where get = snd

-- ** Class 'Set'
class Set ty a where
	set :: ty -> a -> a
instance Set a (a, b) where set a (_, b) = (a, b)
instance Set b (a, b) where set b (a, _) = (a, b)

-- * Class 'Iso'
type Iso ty a = (To ty a, To a ty)

-- ** Class 'To'
class To ty a where
	to :: a -> ty
{-
instance To a a where
	to = id
-}