Control.Monad.Trans.Finish

Short-circuit monad transformer.

Documentation

newtype FinishT f μ α

A monad transformer that extends monad μ with the ability to short-circuit computations with a value of type f.

  runFinishT $ do someStuff
                  when condition $ finish reason
                  otherwiseContinue

Constructors

FinishT

Fields

• runFinishT :: μ (Either f α)

Instances

MonadBase η μ => MonadBase η (FinishT f μ)

Methods

liftBase :: η α -> FinishT f μ α

MonadBaseControl η μ => MonadBaseControl η (FinishT e μ)

Associated Types

type StM (FinishT e μ :: * -> *) a :: *

Methods

liftBaseWith :: (RunInBase (FinishT e μ) η -> η a) -> FinishT e μ a

restoreM :: StM (FinishT e μ) a -> FinishT e μ a

MonadTrans (FinishT f)

Methods

lift :: Monad m => m a -> FinishT f m a

MonadTransControl (FinishT f)

Associated Types

type StT (FinishT f :: (* -> *) -> * -> *) a :: *

Methods

liftWith :: Monad m => (Run (FinishT f) -> m a) -> FinishT f m a

restoreT :: Monad m => m (StT (FinishT f) a) -> FinishT f m a

BindTrans (FinishT f)

Methods

liftB :: Bind b => b a -> FinishT f b a

Monad μ => Monad (FinishT f μ)

Methods

(>>=) :: FinishT f μ a -> (a -> FinishT f μ b) -> FinishT f μ b

(>>) :: FinishT f μ a -> FinishT f μ b -> FinishT f μ b

return :: a -> FinishT f μ a

fail :: String -> FinishT f μ a

Functor μ => Functor (FinishT f μ)

Methods

fmap :: (a -> b) -> FinishT f μ a -> FinishT f μ b

(<$) :: a -> FinishT f μ b -> FinishT f μ a

MonadFix μ => MonadFix (FinishT f μ)

Methods

mfix :: (a -> FinishT f μ a) -> FinishT f μ a

MonadFail μ => MonadFail (FinishT f μ)

Methods

fail :: String -> FinishT f μ a

(Functor μ, Monad μ) => Applicative (FinishT f μ)

Methods

pure :: a -> FinishT f μ a

(<*>) :: FinishT f μ (a -> b) -> FinishT f μ a -> FinishT f μ b

(*>) :: FinishT f μ a -> FinishT f μ b -> FinishT f μ b

(<*) :: FinishT f μ a -> FinishT f μ b -> FinishT f μ a

(Eq f, Eq1 μ) => Eq1 (FinishT f μ)

Methods

liftEq :: (a -> b -> Bool) -> FinishT f μ a -> FinishT f μ b -> Bool

(Ord f, Ord1 μ) => Ord1 (FinishT f μ)

Methods

liftCompare :: (a -> b -> Ordering) -> FinishT f μ a -> FinishT f μ b -> Ordering

(Read f, Read1 μ) => Read1 (FinishT f μ)

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (FinishT f μ a)

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [FinishT f μ a]

(Show f, Show1 μ) => Show1 (FinishT f μ)

Methods

liftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> FinishT f μ a -> ShowS

liftShowList :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> [FinishT f μ a] -> ShowS

MonadZip μ => MonadZip (FinishT f μ)

Methods

mzip :: FinishT f μ a -> FinishT f μ b -> FinishT f μ (a, b)

mzipWith :: (a -> b -> c) -> FinishT f μ a -> FinishT f μ b -> FinishT f μ c

munzip :: FinishT f μ (a, b) -> (FinishT f μ a, FinishT f μ b)

MonadIO μ => MonadIO (FinishT f μ)

Methods

liftIO :: IO a -> FinishT f μ a

Pointed μ => Pointed (FinishT f μ)

Methods

point :: a -> FinishT f μ a

(Functor μ, Monad μ) => Apply (FinishT f μ)

Methods

(<.>) :: FinishT f μ (a -> b) -> FinishT f μ a -> FinishT f μ b

(.>) :: FinishT f μ a -> FinishT f μ b -> FinishT f μ b

(<.) :: FinishT f μ a -> FinishT f μ b -> FinishT f μ a

(Functor μ, Monad μ) => Bind (FinishT f μ)

Methods

(>>-) :: FinishT f μ a -> (a -> FinishT f μ b) -> FinishT f μ b

join :: FinishT f μ (FinishT f μ a) -> FinishT f μ a

(Eq f, Eq1 μ, Eq α) => Eq (FinishT f μ α)

Methods

(==) :: FinishT f μ α -> FinishT f μ α -> Bool

(/=) :: FinishT f μ α -> FinishT f μ α -> Bool

(Ord f, Ord1 μ, Ord α) => Ord (FinishT f μ α)

Methods

compare :: FinishT f μ α -> FinishT f μ α -> Ordering

(<) :: FinishT f μ α -> FinishT f μ α -> Bool

(<=) :: FinishT f μ α -> FinishT f μ α -> Bool

(>) :: FinishT f μ α -> FinishT f μ α -> Bool

(>=) :: FinishT f μ α -> FinishT f μ α -> Bool

max :: FinishT f μ α -> FinishT f μ α -> FinishT f μ α

min :: FinishT f μ α -> FinishT f μ α -> FinishT f μ α

(Read f, Read1 μ, Read α) => Read (FinishT f μ α)

Methods

readsPrec :: Int -> ReadS (FinishT f μ α)

readList :: ReadS [FinishT f μ α]

readPrec :: ReadPrec (FinishT f μ α)

readListPrec :: ReadPrec [FinishT f μ α]

(Show f, Show1 μ, Show α) => Show (FinishT f μ α)

Methods

showsPrec :: Int -> FinishT f μ α -> ShowS

show :: FinishT f μ α -> String

showList :: [FinishT f μ α] -> ShowS

type StT (FinishT f) α

type StT (FinishT f) α = Either f α

type StM (FinishT e μ) α

type StM (FinishT e μ) α = ComposeSt (FinishT e) μ α

runFinishT' :: Monad μ => FinishT α μ α -> μ α

A version of runFinishT for the cases where you don't need to distinguish between short-circuits and regular computation results.

finish :: Monad μ => f -> FinishT f μ α

Short-circuit the enclosing computation.

type Finish f α = FinishT f Identity α

An alias for FinishT over Identity.

runFinish :: Finish f α -> Either f α

runFinishT specialized for Finish.

runFinish' :: Finish α α -> α

runFinishT' specialized to Finish.