{- |

Module : ./Common/Lattice.hs

Description : lattice classes

Copyright : (c) Christian Maeder, DFKI GmbH 2011

License : GPLv2 or higher, see LICENSE.txt

Maintainer : Christian.Maeder@dfki.de

Stability : provisional

Portability : portable

-}

module Common.Lattice where

class (Ord l, Show l) => Lattice l where

cjoin :: l -> l -> l

ctop :: l

bot :: l

instance Lattice () where

cjoin _ _ = ()

ctop = ()

bot = ()

instance Lattice Bool where

cjoin = (||)

ctop = True

bot = False

instance (Lattice a, Lattice b) => Lattice (a, b) where

cjoin (a, b) (c, d) = (cjoin a c, cjoin b d)

ctop = (ctop, ctop)

bot = (bot, bot)