{- | Module : Control.MonadZero.Graph Description : Graph indexed monads with failure Copyright : (c) Aaron Friel License : BSD-3 Maintainer : Aaron Friel <mayreply@aaronfriel.com> Stability : unstable Portability : portable -} {-# LANGUAGE DefaultSignatures #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE MultiParamTypeClasses #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE TypeFamilies #-} -- For the default Apply, Then, and But instances. {-# LANGUAGE UndecidableInstances #-} module Control.MonadZero.Graph where import Control.Graphted.Class import Control.Monad.Graph class GMonad m => GMonadZero (m :: p -> * -> *) where type family Zero m :: p type instance Zero m = Unit m gzero :: m (Zero m) a