Control.Monad.PlusMonad

The Plus monad - a free combination of monads. This is very similar to coproducts, but not quite the same.

Coproducts are due to Luth and Ghani, "Composing Monads Using Coproducts," http://www.informatik.uni-bremen.de/~cxl/papers/icfp02.pdf

Documentation

newtype (m ::+ n) t

Constructors

Plus

Fields

unPlus :: forall x. MonadPlus x => (forall u. m u -> x u) -> (forall u. n u -> x u) -> x t

Instances

Lifter m ((::+) m n)

MFunctor ((::+) m)

MonadPlus m => MMonad ((::+) m)

MonadTrans ((::+) m)

Alternative ((::+) m n)

Monad ((::+) m n)

Functor ((::+) m n)

MonadPlus ((::+) m n)

Applicative ((::+) m n)

inl :: m t -> (::+) m n t

inr :: n t -> (::+) m n t

mapPlus :: (forall t. m t -> m1 t) -> (forall t. n t -> n1 t) -> (m ::+ n) t -> (m1 ::+ n1) t

comm :: (m ::+ n) t -> (n ::+ m) t

assoc :: (::+) ((::+) m n) n1 t -> (::+) m ((::+) n n1) t

assoc1 :: (::+) t ((::+) n1 n) t1 -> (::+) ((::+) t n1) n t1

cancelLeft :: MonadPlus t => (::+) Identity t t1 -> t t1

cancelRight :: MonadPlus t => (::+) t Identity t1 -> t t1

refl :: MonadPlus t => (::+) t t t1 -> t t1

distr :: (::+) (Product m1 h) (Product n1 h1) a -> Product ((::+) m1 n1) ((::+) h h1) a

Distributivity with monad products.