Copyright	©2020 James Alexander Feldman-Crough
License	MPL-2.0
Maintainer	alex@fldcr.com
Safe Haskell	Safe
Language	Haskell2010

Data.Either.Valid

Description

Synopsis

data Valid e a
- = Invalid !e
- | Valid !a
fromEither :: Either e a -> Valid e a
toEither :: Valid e a -> Either e a
valid :: (e -> r) -> (a -> r) -> Valid e a -> r

Documentation

data Valid e a Source #

Like the Either type, but its instances accumulates its errors. As such, there is no Monad instance for Valid.

The Invalid constructor takes precedence over Valid when used with classes that combine two values.

Note: There are a lot of packages that implement this data type, but finding a well-maintained one with minimal dependencies proved difficult.

Constructors

Invalid !e
Valid !a

Instances

Instances details

Bifunctor Valid Source #
Instance details Defined in Data.Either.Valid Methods bimap :: (a -> b) -> (c -> d) -> Valid a c -> Valid b d # first :: (a -> b) -> Valid a c -> Valid b c # second :: (b -> c) -> Valid a b -> Valid a c #
Functor (Valid e) Source #
Instance details Defined in Data.Either.Valid Methods fmap :: (a -> b) -> Valid e a -> Valid e b # (<$) :: a -> Valid e b -> Valid e a #
Semigroup e => Applicative (Valid e) Source #
Instance details Defined in Data.Either.Valid Methods pure :: a -> Valid e a # (<>) :: Valid e (a -> b) -> Valid e a -> Valid e b # liftA2 :: (a -> b -> c) -> Valid e a -> Valid e b -> Valid e c # (>) :: Valid e a -> Valid e b -> Valid e b # (<*) :: Valid e a -> Valid e b -> Valid e a #
Monoid e => Alternative (Valid e) Source #
Instance details Defined in Data.Either.Valid Methods empty :: Valid e a # (<\|>) :: Valid e a -> Valid e a -> Valid e a # some :: Valid e a -> Valid e [a] # many :: Valid e a -> Valid e [a] #
(Eq e, Eq a) => Eq (Valid e a) Source #
Instance details Defined in Data.Either.Valid Methods (==) :: Valid e a -> Valid e a -> Bool # (/=) :: Valid e a -> Valid e a -> Bool #
(Ord e, Ord a) => Ord (Valid e a) Source #
Instance details Defined in Data.Either.Valid Methods compare :: Valid e a -> Valid e a -> Ordering # (<) :: Valid e a -> Valid e a -> Bool # (<=) :: Valid e a -> Valid e a -> Bool # (>) :: Valid e a -> Valid e a -> Bool # (>=) :: Valid e a -> Valid e a -> Bool # max :: Valid e a -> Valid e a -> Valid e a # min :: Valid e a -> Valid e a -> Valid e a #
(Show e, Show a) => Show (Valid e a) Source #
Instance details Defined in Data.Either.Valid Methods showsPrec :: Int -> Valid e a -> ShowS # show :: Valid e a -> String # showList :: [Valid e a] -> ShowS #
(Semigroup e, Semigroup a) => Semigroup (Valid e a) Source #
Instance details Defined in Data.Either.Valid Methods (<>) :: Valid e a -> Valid e a -> Valid e a # sconcat :: NonEmpty (Valid e a) -> Valid e a # stimes :: Integral b => b -> Valid e a -> Valid e a #
(Semigroup e, Monoid a) => Monoid (Valid e a) Source #
Instance details Defined in Data.Either.Valid Methods mempty :: Valid e a # mappend :: Valid e a -> Valid e a -> Valid e a # mconcat :: [Valid e a] -> Valid e a #

fromEither :: Either e a -> Valid e a Source #

Convert an Either value to Valid.

toEither :: Valid e a -> Either e a Source #

Convert a Valid value to Either.

valid :: (e -> r) -> (a -> r) -> Valid e a -> r Source #

Consume a Valid by handling errors and valid values.