Control.Monad.Class.Choice

Documentation

class Monad m => MonadChoice f m where

A monad with a series of dependent choices. It is usually desirable to have f be a Foldable so that a selection can be made from it.

As an example here is a simple berry name generator:

berry :: MonadChoice NonEmpty m => m String
berry = do
  color  <- choose $ "red" :| ["blue", "pink", "cyan"]
  prefix <- choose $ "color" :| ["straw", "rasp", "cran"]
  return $ prefix ++ "berry"

Since this has a polymorphic type this could be used for a variety of purposes.

Methods

choose :: f a -> m a

Makes a selection.

Instances

(Foldable f, MonadRandom m) => MonadChoice f m

Defined in Control.Monad.Class.Choice

Methods

choose :: f a -> m a

MonadChoice f m => MonadChoice f (MaybeT m)

Defined in Control.Monad.Class.Choice

Methods

choose :: f a -> MaybeT m a

MonadChoice f m => MonadChoice f (SelectT r m)

Defined in Control.Monad.Class.Choice

Methods

choose :: f a -> SelectT r m a

(Monoid w, MonadChoice f m) => MonadChoice f (AccumT w m)

Defined in Control.Monad.Class.Choice

Methods

choose :: f a -> AccumT w m a

(Monoid w, MonadChoice f m) => MonadChoice f (WriterT w m)

Defined in Control.Monad.Class.Choice

Methods

choose :: f a -> WriterT w m a

(Monoid w, MonadChoice f m) => MonadChoice f (WriterT w m)

Defined in Control.Monad.Class.Choice

Methods

choose :: f a -> WriterT w m a

MonadChoice f m => MonadChoice f (WriterT w m)

Defined in Control.Monad.Class.Choice

Methods

choose :: f a -> WriterT w m a

MonadChoice f m => MonadChoice f (ReaderT r m)

Defined in Control.Monad.Class.Choice

Methods

choose :: f a -> ReaderT r m a

MonadChoice f m => MonadChoice f (StateT s m)

Defined in Control.Monad.Class.Choice

Methods

choose :: f a -> StateT s m a

MonadChoice f m => MonadChoice f (StateT s m)

Defined in Control.Monad.Class.Choice

Methods

choose :: f a -> StateT s m a

MonadChoice f m => MonadChoice f (IdentityT m)

Defined in Control.Monad.Class.Choice

Methods

choose :: f a -> IdentityT m a

MonadChoice f m => MonadChoice f (ExceptT e m)

Defined in Control.Monad.Class.Choice

Methods

choose :: f a -> ExceptT e m a

MonadChoice f (ChoiceT f m)

Defined in Control.Monad.Trans.Choice.Covariant

Methods

choose :: f a -> ChoiceT f m a

Monad m => MonadChoice f (ChoiceT f m)

Defined in Control.Monad.Trans.Choice.Invariant

Methods

choose :: f a -> ChoiceT f m a

MonadChoice f m => MonadChoice f (ContT r m)

Defined in Control.Monad.Class.Choice

Methods

choose :: f a -> ContT r m a

MonadChoice f m => MonadChoice f (RWST r w s m)

Defined in Control.Monad.Class.Choice

Methods

choose :: f a -> RWST r w s m a

(Monoid w, MonadChoice f m) => MonadChoice f (RWST r w s m)

Defined in Control.Monad.Class.Choice

Methods

choose :: f a -> RWST r w s m a

(Monoid w, MonadChoice f m) => MonadChoice f (RWST r w s m)

Defined in Control.Monad.Class.Choice

Methods

choose :: f a -> RWST r w s m a

chooseM :: MonadChoice f m => f (m a) -> m a

Makes a selection where options are themselves selections.