Control.Monad.Trail

Trail type which makes an ordinary Monad out of FMonad

Documentation

newtype Trail mm a

For any FMonad mm, Trail mm is a Monad.

Example

Trail mm can become variantions of Monad for different FMonad mm.

• mm = Compose m

  For any Monad m, Trail (Compose m) is isomorphic to m.

  Trail (Compose m) a
    ~ Compose m ((,) a) ()
    ~ m (a, ())
    ~ m a
  

• mm = Free

  Trail Free is isomorphic to the list monad [].

  Trail Free a
    ~ Free ((,) a) ()
    ~ [a]
  

• mm = FreeT' m

  For any Monad m, Trail (FreeT' m) is isomorphic to ListT m, where ListT is so-called "ListT done right."

  Trail (FreeT' m) a
    ~ FreeT ((,) a) m ()
    ~ ListT m a
  

  See more for examples/ListTVia.hs

Constructors

Trail

Fields

• runTrail :: mm ((,) a) ()

Instances

FMonad mm => Applicative (Trail mm)

Defined in Control.Monad.Trail

Methods

pure :: a -> Trail mm a

(<*>) :: Trail mm (a -> b) -> Trail mm a -> Trail mm b

liftA2 :: (a -> b -> c) -> Trail mm a -> Trail mm b -> Trail mm c

(*>) :: Trail mm a -> Trail mm b -> Trail mm b

(<*) :: Trail mm a -> Trail mm b -> Trail mm a

FFunctor mm => Functor (Trail mm)

Defined in Control.Monad.Trail

Methods

fmap :: (a -> b) -> Trail mm a -> Trail mm b

(<$) :: a -> Trail mm b -> Trail mm a

FMonad mm => Monad (Trail mm)

Defined in Control.Monad.Trail

Methods

(>>=) :: Trail mm a -> (a -> Trail mm b) -> Trail mm b

(>>) :: Trail mm a -> Trail mm b -> Trail mm b

return :: a -> Trail mm a