Control.Monad.Trans.Result

ResultT interfaces with Result.

The Result monad

type Result = ResultT Identity

A result monad.

pattern Result :: Either String a -> Result a

Wrap Result a.

runResult :: Result a -> Either String a

Unrap Result a.

pattern Error :: String -> Result a

Error means errors and failures etc.

pattern Success :: a -> Result a

Success means successes and OKs etc.

result :: (String -> b) -> (a -> b) -> Result a -> b

Case analysis for the Result type.

Examples

>>> let s = Success 0
>>> let e = Error "critical"
>>> result ("Bad: " ++) (("OK: " ++) . show) s
"OK: 0"
>>> result ("Bad: " ++) (("OK: " ++) . show) e
"Bad: critical"

fromEither :: Either String a -> Result a

Convert Either String a to Result a.

toEither :: Result a -> Either String a

Convert Result a to Either String a.

fromSuccess :: a -> Result a -> a

Convert Result a to a with a default value.

toMonadFail :: MonadFail m => Result a -> m a

Convert Result a to MonadFail m => m a.

The ResultT monad transformer

data ResultT m a

A monad transformer that is similar to ExceptT except a MonadFail instance.

MonadFail = ResultT . throwE

Instances

MonadTrans ResultT

Defined in Control.Monad.Trans.Except.Result

Methods

lift :: Monad m => m a -> ResultT m a

Monad m => MonadError String (ResultT m)

Defined in Control.Monad.Result

Methods

throwError :: String -> ResultT m a

catchError :: ResultT m a -> (String -> ResultT m a) -> ResultT m a

Monad m => Monad (ResultT m)

Defined in Control.Monad.Trans.Except.Result

Methods

(>>=) :: ResultT m a -> (a -> ResultT m b) -> ResultT m b

(>>) :: ResultT m a -> ResultT m b -> ResultT m b

return :: a -> ResultT m a

fail :: String -> ResultT m a

Functor m => Functor (ResultT m)

Defined in Control.Monad.Trans.Except.Result

Methods

fmap :: (a -> b) -> ResultT m a -> ResultT m b

(<$) :: a -> ResultT m b -> ResultT m a

Read a => Read (Result a)

Defined in Control.Monad.Trans.Result

Methods

readsPrec :: Int -> ReadS (Result a)

readList :: ReadS [Result a]

readPrec :: ReadPrec (Result a)

readListPrec :: ReadPrec [Result a]

Show a => Show (Result a)

Defined in Control.Monad.Trans.Result

Methods

showsPrec :: Int -> Result a -> ShowS

show :: Result a -> String

showList :: [Result a] -> ShowS

MonadFix m => MonadFix (ResultT m)

Defined in Control.Monad.Trans.Except.Result

Methods

mfix :: (a -> ResultT m a) -> ResultT m a

Monad m => MonadFail (ResultT m)

Defined in Control.Monad.Trans.Except.Result

Methods

fail :: String -> ResultT m a

Monad m => Applicative (ResultT m)

Defined in Control.Monad.Trans.Except.Result

Methods

pure :: a -> ResultT m a

(<*>) :: ResultT m (a -> b) -> ResultT m a -> ResultT m b

liftA2 :: (a -> b -> c) -> ResultT m a -> ResultT m b -> ResultT m c

(*>) :: ResultT m a -> ResultT m b -> ResultT m b

(<*) :: ResultT m a -> ResultT m b -> ResultT m a

Foldable m => Foldable (ResultT m)

Defined in Control.Monad.Trans.Except.Result

Methods

fold :: Monoid m0 => ResultT m m0 -> m0

foldMap :: Monoid m0 => (a -> m0) -> ResultT m a -> m0

foldr :: (a -> b -> b) -> b -> ResultT m a -> b

foldr' :: (a -> b -> b) -> b -> ResultT m a -> b

foldl :: (b -> a -> b) -> b -> ResultT m a -> b

foldl' :: (b -> a -> b) -> b -> ResultT m a -> b

foldr1 :: (a -> a -> a) -> ResultT m a -> a

foldl1 :: (a -> a -> a) -> ResultT m a -> a

toList :: ResultT m a -> [a]

null :: ResultT m a -> Bool

length :: ResultT m a -> Int

elem :: Eq a => a -> ResultT m a -> Bool

maximum :: Ord a => ResultT m a -> a

minimum :: Ord a => ResultT m a -> a

sum :: Num a => ResultT m a -> a

product :: Num a => ResultT m a -> a

Traversable m => Traversable (ResultT m)

Defined in Control.Monad.Trans.Except.Result

Methods

traverse :: Applicative f => (a -> f b) -> ResultT m a -> f (ResultT m b)

sequenceA :: Applicative f => ResultT m (f a) -> f (ResultT m a)

mapM :: Monad m0 => (a -> m0 b) -> ResultT m a -> m0 (ResultT m b)

sequence :: Monad m0 => ResultT m (m0 a) -> m0 (ResultT m a)

Semigroup (Result a)

Defined in Control.Monad.Trans.Result

Methods

(<>) :: Result a -> Result a -> Result a

sconcat :: NonEmpty (Result a) -> Result a

stimes :: Integral b => b -> Result a -> Result a

Monoid (Result a)

Defined in Control.Monad.Trans.Result

Methods

mempty :: Result a

mappend :: Result a -> Result a -> Result a

mconcat :: [Result a] -> Result a

Contravariant m => Contravariant (ResultT m)

Defined in Control.Monad.Trans.Except.Result

Methods

contramap :: (a -> b) -> ResultT m b -> ResultT m a

(>$) :: b -> ResultT m b -> ResultT m a

Eq1 m => Eq1 (ResultT m)

Defined in Control.Monad.Trans.Except.Result

Methods

liftEq :: (a -> b -> Bool) -> ResultT m a -> ResultT m b -> Bool

Ord1 m => Ord1 (ResultT m)

Defined in Control.Monad.Trans.Except.Result

Methods

liftCompare :: (a -> b -> Ordering) -> ResultT m a -> ResultT m b -> Ordering

Read1 m => Read1 (ResultT m)

Defined in Control.Monad.Trans.Except.Result

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (ResultT m a)

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [ResultT m a]

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (ResultT m a)

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [ResultT m a]

Show1 m => Show1 (ResultT m)

Defined in Control.Monad.Trans.Except.Result

Methods

liftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> ResultT m a -> ShowS

liftShowList :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> [ResultT m a] -> ShowS

MonadZip m => MonadZip (ResultT m)

Defined in Control.Monad.Trans.Except.Result

Methods

mzip :: ResultT m a -> ResultT m b -> ResultT m (a, b)

mzipWith :: (a -> b -> c) -> ResultT m a -> ResultT m b -> ResultT m c

munzip :: ResultT m (a, b) -> (ResultT m a, ResultT m b)

MonadIO m => MonadIO (ResultT m)

Defined in Control.Monad.Trans.Except.Result

Methods

liftIO :: IO a -> ResultT m a

Monad m => Alternative (ResultT m)

Defined in Control.Monad.Trans.Except.Result

Methods

empty :: ResultT m a

(<|>) :: ResultT m a -> ResultT m a -> ResultT m a

some :: ResultT m a -> ResultT m [a]

many :: ResultT m a -> ResultT m [a]

Monad m => MonadPlus (ResultT m)

Defined in Control.Monad.Trans.Except.Result

Methods

mzero :: ResultT m a

mplus :: ResultT m a -> ResultT m a -> ResultT m a

(Eq1 m, Eq a) => Eq (ResultT m a)

Defined in Control.Monad.Trans.Except.Result

Methods

(==) :: ResultT m a -> ResultT m a -> Bool

(/=) :: ResultT m a -> ResultT m a -> Bool

(Ord1 m, Ord a) => Ord (ResultT m a)

Defined in Control.Monad.Trans.Except.Result

Methods

compare :: ResultT m a -> ResultT m a -> Ordering

(<) :: ResultT m a -> ResultT m a -> Bool

(<=) :: ResultT m a -> ResultT m a -> Bool

(>) :: ResultT m a -> ResultT m a -> Bool

(>=) :: ResultT m a -> ResultT m a -> Bool

max :: ResultT m a -> ResultT m a -> ResultT m a

min :: ResultT m a -> ResultT m a -> ResultT m a

(Read1 m, Read a) => Read (ResultT m a)

Defined in Control.Monad.Trans.Except.Result

Methods

readsPrec :: Int -> ReadS (ResultT m a)

readList :: ReadS [ResultT m a]

readPrec :: ReadPrec (ResultT m a)

readListPrec :: ReadPrec [ResultT m a]

(Show1 m, Show a) => Show (ResultT m a)

Defined in Control.Monad.Trans.Except.Result

Methods

showsPrec :: Int -> ResultT m a -> ShowS

show :: ResultT m a -> String

showList :: [ResultT m a] -> ShowS

Generic (ResultT m a)

Defined in Control.Monad.Trans.Except.Result

Associated Types

type Rep (ResultT m a) :: Type -> Type

Methods

from :: ResultT m a -> Rep (ResultT m a) x

to :: Rep (ResultT m a) x -> ResultT m a

type Rep (ResultT m a)

Defined in Control.Monad.Trans.Except.Result

type Rep (ResultT m a) = D1 (MetaData "ResultT" "Control.Monad.Trans.Except.Result" "either-result-0.2.0.0-CJRPI8v50W54nBJM71G0Zx" True) (C1 (MetaCons "ResultT" PrefixI True) (S1 (MetaSel (Just "runResultT") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (ExceptT String m a))))

pattern ResultT :: Functor m => m (Either String a) -> ResultT m a

Construct and destruct Result.

runResultT :: Functor m => ResultT m a -> m (Either String a)

Unwrap ResultT.

mapResultT :: (Functor m, Functor n) => (m (Either String a) -> n (Either String b)) -> ResultT m a -> ResultT n b

Map the unwrapped computation using the given function.

Exception operations

throwE :: Monad m => String -> ResultT m a

Signal an exception.

catchE :: Monad m => ResultT m a -> (String -> ResultT m a) -> ResultT m a

Handle an exception.

Lifting other operations

liftCallCC :: CallCC m (Either String a) (Either String b) -> CallCC (ResultT m) a b

Lift a callCC operation to the new monad.

liftListen :: Monad m => Listen w m (Either String a) -> Listen w (ResultT m) a

Lift a listen operation to the new monad.

liftPass :: Monad m => Pass w m (Either String a) -> Pass w (ResultT m) a

Lift a pass operation to the new monad.

Orphan instances

Read a => Read (Result a)

Methods

readsPrec :: Int -> ReadS (Result a)

readList :: ReadS [Result a]

readPrec :: ReadPrec (Result a)

readListPrec :: ReadPrec [Result a]

Show a => Show (Result a)

Methods

showsPrec :: Int -> Result a -> ShowS

show :: Result a -> String

showList :: [Result a] -> ShowS

Semigroup (Result a)

Methods

(<>) :: Result a -> Result a -> Result a

sconcat :: NonEmpty (Result a) -> Result a

stimes :: Integral b => b -> Result a -> Result a

Monoid (Result a)

Methods

mempty :: Result a

mappend :: Result a -> Result a -> Result a

mconcat :: [Result a] -> Result a