crdt-0.2: lib/Data/Semilattice.hs

module Data.Semilattice
    ( Semilattice
    , (<>)
    ) where

import           Data.Semigroup (Semigroup)
import qualified Data.Semigroup as Semigroup

{- |
A semilattice.

It may be a join-semilattice, or meet-semilattice, it doesn't matter.

If it matters for you, use package @lattices@.

In addition to 'Semigroup', Semilattice defines this laws:

[commutativity]

    @x '<>' y == y '<>' x@

[idempotency]

    @x '<>' x == x@
-}
class Semigroup a => Semilattice a

-- | Just ('Semigroup.<>'), specialized to 'Semilattice'.
(<>) :: Semilattice a => a -> a -> a
(<>) = (Semigroup.<>)
infixr 6 <>
{-# INLINE (<>) #-}