Accuerr

Provides Accuerr, a type similar to Either but where the Applicative instance accumulates error values. This module is based on work in the validation package, which is available at

https://hackage.haskell.org/package/validation

The main differences between the validation package and this one:

• validation has more data types, many of which overlap with those available in other packages. This package sticks with the Accuerr type only.
• This package works with GHC 8; as of 2016-06-11, validation does not.
• Accuerr has fewer typeclass instances than its corresponding type in validation.

Documentation

data Accuerr e a

A type similar to Either but the Applicative instance accumulates error values. Unlike Either, there is no Monad instance, because there is no >>= such that ap equals <*>.

For the Applicative instance to work, your error type must be a Semigroup, such as a list or a NonEmpty.

Examples

>>> import Text.Read
>>> :{
       let readInt x = case readMaybe x of
             Nothing -> AccFailure [x]
             Just a -> AccSuccess a
               where _types = a :: Int
    :}

>>> (+) <$> readInt "3" <*> readInt "4"
AccSuccess 7
>>> (+) <$> readInt "x3" <*> readInt "4"
AccFailure ["x3"]
>>> (+) <$> readInt "x3" <*> readInt "x4"
AccFailure ["x3","x4"]
>>> (,,) <$> readInt "3" <*> readInt "4" <*> readInt "x5"
AccFailure ["x5"]
>>> sequenceA [AccSuccess 3, AccSuccess 4]
AccSuccess [3,4]
>>> sequenceA [AccSuccess 3, AccSuccess 4, AccFailure ['c'], AccFailure ['a']]
AccFailure "ca"

Constructors

AccFailure e

AccSuccess a

Instances

Bifunctor Accuerr

Methods

bimap :: (a -> b) -> (c -> d) -> Accuerr a c -> Accuerr b d

first :: (a -> b) -> Accuerr a c -> Accuerr b c

second :: (b -> c) -> Accuerr a b -> Accuerr a c

Bitraversable Accuerr

Methods

bitraverse :: Applicative f => (a -> f c) -> (b -> f d) -> Accuerr a b -> f (Accuerr c d)

Bifoldable Accuerr

Methods

bifold :: Monoid m => Accuerr m m -> m

bifoldMap :: Monoid m => (a -> m) -> (b -> m) -> Accuerr a b -> m

bifoldr :: (a -> c -> c) -> (b -> c -> c) -> c -> Accuerr a b -> c

bifoldl :: (c -> a -> c) -> (c -> b -> c) -> c -> Accuerr a b -> c

Swapped Accuerr

Methods

swapped :: (Profunctor p, Functor f) => p (Accuerr b a) (f (Accuerr d c)) -> p (Accuerr a b) (f (Accuerr c d))

Functor (Accuerr e)

Methods

fmap :: (a -> b) -> Accuerr e a -> Accuerr e b

(<$) :: a -> Accuerr e b -> Accuerr e a

Semigroup e => Applicative (Accuerr e)

Methods

pure :: a -> Accuerr e a

(<*>) :: Accuerr e (a -> b) -> Accuerr e a -> Accuerr e b

(*>) :: Accuerr e a -> Accuerr e b -> Accuerr e b

(<*) :: Accuerr e a -> Accuerr e b -> Accuerr e a

Foldable (Accuerr e)

Methods

fold :: Monoid m => Accuerr e m -> m

foldMap :: Monoid m => (a -> m) -> Accuerr e a -> m

foldr :: (a -> b -> b) -> b -> Accuerr e a -> b

foldr' :: (a -> b -> b) -> b -> Accuerr e a -> b

foldl :: (b -> a -> b) -> b -> Accuerr e a -> b

foldl' :: (b -> a -> b) -> b -> Accuerr e a -> b

foldr1 :: (a -> a -> a) -> Accuerr e a -> a

foldl1 :: (a -> a -> a) -> Accuerr e a -> a

toList :: Accuerr e a -> [a]

null :: Accuerr e a -> Bool

length :: Accuerr e a -> Int

elem :: Eq a => a -> Accuerr e a -> Bool

maximum :: Ord a => Accuerr e a -> a

minimum :: Ord a => Accuerr e a -> a

sum :: Num a => Accuerr e a -> a

product :: Num a => Accuerr e a -> a

Traversable (Accuerr e)

Methods

traverse :: Applicative f => (a -> f b) -> Accuerr e a -> f (Accuerr e b)

sequenceA :: Applicative f => Accuerr e (f a) -> f (Accuerr e a)

mapM :: Monad m => (a -> m b) -> Accuerr e a -> m (Accuerr e b)

sequence :: Monad m => Accuerr e (m a) -> m (Accuerr e a)

(Eq e, Eq a) => Eq (Accuerr e a)

Methods

(==) :: Accuerr e a -> Accuerr e a -> Bool

(/=) :: Accuerr e a -> Accuerr e a -> Bool

(Ord e, Ord a) => Ord (Accuerr e a)

Methods

compare :: Accuerr e a -> Accuerr e a -> Ordering

(<) :: Accuerr e a -> Accuerr e a -> Bool

(<=) :: Accuerr e a -> Accuerr e a -> Bool

(>) :: Accuerr e a -> Accuerr e a -> Bool

(>=) :: Accuerr e a -> Accuerr e a -> Bool

max :: Accuerr e a -> Accuerr e a -> Accuerr e a

min :: Accuerr e a -> Accuerr e a -> Accuerr e a

(Show e, Show a) => Show (Accuerr e a)

Methods

showsPrec :: Int -> Accuerr e a -> ShowS

show :: Accuerr e a -> String

showList :: [Accuerr e a] -> ShowS

_AccSuccess :: forall e a a. Prism (Accuerr e a) (Accuerr e a) a a

_AccFailure :: forall e a e. Prism (Accuerr e a) (Accuerr e a) e e

accuerr :: (a -> c) -> (b -> c) -> Accuerr a b -> c

Case analysis for the Accuerr type. Like either.

accuerrToEither :: Accuerr e a -> Either e a

eitherToAccuerr :: Either e a -> Accuerr e a

isoAccuerrEither :: Iso' (Accuerr e a) (Either e a)

isoEitherAccuerr :: Iso' (Either e a) (Accuerr e a)