pandora-0.3.2: Pandora/Pattern/Functor/Monad.hs

module Pandora.Pattern.Functor.Monad where

import Pandora.Pattern.Functor.Bindable (Bindable ((>>=)))
import Pandora.Pattern.Functor.Pointable (Pointable (point))

{- |
> Let f :: (Pointable t, Bindable t) => a -> t a
> Let g :: (Pointable t, Bindable t) => a -> t a
> Let h :: (Pointable t, Bindable t) => t a

> When providing a new instance, you should ensure it satisfies the three laws:
> * Left identity: point a >>= f ≡ f a
> * Right identity: h >>= point ≡ h
> * Associativity: h >>= (f >=> g) ≡ (h >>= f) >>= g
-}

infixl 1 >>=-, ->>=
infixr 1 -=<<, =<<-

class (Pointable t, Bindable t) => Monad t where
	(>>=-) :: t a -> t b -> t a
	(>>=-) x y = x >>= \r -> y >>= \_ -> point r
	(->>=) :: t a -> t b -> t b
	(->>=) x y = x >>= \_ -> y >>= \r -> point r
	(-=<<) :: t a -> t b -> t b
	(-=<<) x y = x >>= \_ -> y >>= \r -> point r
	(=<<-) :: t a -> t b -> t a
	(=<<-) x y = x >>= \r -> y >>= \_ -> point r