Safe Haskell	None
Language	Haskell98

Data.These

Contents

Functions to get rid of These
Traversals
Prisms
Case selections
Case predicates
Map operations

Description

The These type and associated operations. Now enhanced with Control.Lens magic!

Synopsis

Documentation

data These a b Source #

The These type represents values with two non-exclusive possibilities.

This can be useful to represent combinations of two values, where the combination is defined if either input is. Algebraically, the type These A B represents (A + B + AB), which doesn't factor easily into sums and products--a type like Either A (B, Maybe A) is unclear and awkward to use.

These has straightforward instances of Functor, Monad, &c., and behaves like a hybrid error/writer monad, as would be expected.

Constructors

This a
That b
These a b

Instances

Arbitrary2 These Source #
Methods liftArbitrary2 :: Gen a -> Gen b -> Gen (These a b) # liftShrink2 :: (a -> [a]) -> (b -> [b]) -> These a b -> [These a b] #
ToJSON2 These Source #
Methods liftToJSON2 :: (a -> Value) -> ([a] -> Value) -> (b -> Value) -> ([b] -> Value) -> These a b -> Value # liftToJSONList2 :: (a -> Value) -> ([a] -> Value) -> (b -> Value) -> ([b] -> Value) -> [These a b] -> Value # liftToEncoding2 :: (a -> Encoding) -> ([a] -> Encoding) -> (b -> Encoding) -> ([b] -> Encoding) -> These a b -> Encoding # liftToEncodingList2 :: (a -> Encoding) -> ([a] -> Encoding) -> (b -> Encoding) -> ([b] -> Encoding) -> [These a b] -> Encoding #
FromJSON2 These Source #
Methods liftParseJSON2 :: (Value -> Parser a) -> (Value -> Parser [a]) -> (Value -> Parser b) -> (Value -> Parser [b]) -> Value -> Parser (These a b) # liftParseJSONList2 :: (Value -> Parser a) -> (Value -> Parser [a]) -> (Value -> Parser b) -> (Value -> Parser [b]) -> Value -> Parser [These a b] #
Bifunctor These Source #
Methods bimap :: (a -> b) -> (c -> d) -> These a c -> These b d # first :: (a -> b) -> These a c -> These b c # second :: (b -> c) -> These a b -> These a c #
Bitraversable These Source #
Methods bitraverse :: Applicative f => (a -> f c) -> (b -> f d) -> These a b -> f (These c d) #
Bifoldable These Source #
Methods bifold :: Monoid m => These m m -> m # bifoldMap :: Monoid m => (a -> m) -> (b -> m) -> These a b -> m # bifoldr :: (a -> c -> c) -> (b -> c -> c) -> c -> These a b -> c # bifoldl :: (c -> a -> c) -> (c -> b -> c) -> c -> These a b -> c #
Bitraversable1 These Source #
Methods bitraverse1 :: Apply f => (a -> f b) -> (c -> f d) -> These a c -> f (These b d) # bisequence1 :: Apply f => These (f a) (f b) -> f (These a b) #
Bifoldable1 These Source #
Methods bifold1 :: Semigroup m => These m m -> m # bifoldMap1 :: Semigroup m => (a -> m) -> (b -> m) -> These a b -> m #
Bicrosswalk These Source #
Methods bicrosswalk :: Align f => (a -> f c) -> (b -> f d) -> These a b -> f (These c d) Source # bisequenceL :: Align f => These (f a) (f b) -> f (These a b) Source #
Semigroup c => MonadChronicle c (These c) Source #
Methods dictate :: c -> These c () Source # disclose :: Default a => c -> These c a Source # confess :: c -> These c a Source # memento :: These c a -> These c (Either c a) Source # absolve :: a -> These c a -> These c a Source # condemn :: These c a -> These c a Source # retcon :: (c -> c) -> These c a -> These c a Source # chronicle :: These c a -> These c a Source #
Semigroup a => Monad (These a) Source #
Methods (>>=) :: These a a -> (a -> These a b) -> These a b # (>>) :: These a a -> These a b -> These a b # return :: a -> These a a # fail :: String -> These a a #
Functor (These a) Source #
Methods fmap :: (a -> b) -> These a a -> These a b # (<$) :: a -> These a b -> These a a #
Semigroup a => Applicative (These a) Source #
Methods pure :: a -> These a a # (<>) :: These a (a -> b) -> These a a -> These a b # (>) :: These a a -> These a b -> These a b # (<*) :: These a a -> These a b -> These a a #
Foldable (These a) Source #
Methods fold :: Monoid m => These a m -> m # foldMap :: Monoid m => (a -> m) -> These a a -> m # foldr :: (a -> b -> b) -> b -> These a a -> b # foldr' :: (a -> b -> b) -> b -> These a a -> b # foldl :: (b -> a -> b) -> b -> These a a -> b # foldl' :: (b -> a -> b) -> b -> These a a -> b # foldr1 :: (a -> a -> a) -> These a a -> a # foldl1 :: (a -> a -> a) -> These a a -> a # toList :: These a a -> [a] # null :: These a a -> Bool # length :: These a a -> Int # elem :: Eq a => a -> These a a -> Bool # maximum :: Ord a => These a a -> a # minimum :: Ord a => These a a -> a # sum :: Num a => These a a -> a # product :: Num a => These a a -> a #
Traversable (These a) Source #
Methods traverse :: Applicative f => (a -> f b) -> These a a -> f (These a b) # sequenceA :: Applicative f => These a (f a) -> f (These a a) # mapM :: Monad m => (a -> m b) -> These a a -> m (These a b) # sequence :: Monad m => These a (m a) -> m (These a a) #
Arbitrary a => Arbitrary1 (These a) Source #
Methods liftArbitrary :: Gen a -> Gen (These a a) # liftShrink :: (a -> [a]) -> These a a -> [These a a] #
ToJSON a => ToJSON1 (These a) Source #
Methods liftToJSON :: (a -> Value) -> ([a] -> Value) -> These a a -> Value # liftToJSONList :: (a -> Value) -> ([a] -> Value) -> [These a a] -> Value # liftToEncoding :: (a -> Encoding) -> ([a] -> Encoding) -> These a a -> Encoding # liftToEncodingList :: (a -> Encoding) -> ([a] -> Encoding) -> [These a a] -> Encoding #
FromJSON a => FromJSON1 (These a) Source #
Methods liftParseJSON :: (Value -> Parser a) -> (Value -> Parser [a]) -> Value -> Parser (These a a) # liftParseJSONList :: (Value -> Parser a) -> (Value -> Parser [a]) -> Value -> Parser [These a a] #
Semigroup a => Apply (These a) Source #
Methods (<.>) :: These a (a -> b) -> These a a -> These a b # (.>) :: These a a -> These a b -> These a b # (<.) :: These a a -> These a b -> These a a #
Semigroup a => Bind (These a) Source #
Methods (>>-) :: These a a -> (a -> These a b) -> These a b # join :: These a (These a a) -> These a a #
Crosswalk (These a) Source #
Methods crosswalk :: Align f => (a -> f b) -> These a a -> f (These a b) Source # sequenceL :: Align f => These a (f a) -> f (These a a) Source #
(Eq b, Eq a) => Eq (These a b) Source #
Methods (==) :: These a b -> These a b -> Bool # (/=) :: These a b -> These a b -> Bool #
(Data b, Data a) => Data (These a b) Source #
Methods gfoldl :: (forall d c. Data d => c (d -> c) -> d -> c c) -> (forall g. g -> c g) -> These a b -> c (These a b) # gunfold :: (forall c r. Data c => c (c -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (These a b) # toConstr :: These a b -> Constr # dataTypeOf :: These a b -> DataType # dataCast1 :: Typeable (* -> ) t => (forall d. Data d => c (t d)) -> Maybe (c (These a b)) # dataCast2 :: Typeable ( -> * -> *) t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (These a b)) # gmapT :: (forall c. Data c => c -> c) -> These a b -> These a b # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> These a b -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> These a b -> r # gmapQ :: (forall d. Data d => d -> u) -> These a b -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> These a b -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> These a b -> m (These a b) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> These a b -> m (These a b) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> These a b -> m (These a b) #
(Ord b, Ord a) => Ord (These a b) Source #
Methods compare :: These a b -> These a b -> Ordering # (<) :: These a b -> These a b -> Bool # (<=) :: These a b -> These a b -> Bool # (>) :: These a b -> These a b -> Bool # (>=) :: These a b -> These a b -> Bool # max :: These a b -> These a b -> These a b # min :: These a b -> These a b -> These a b #
(Read b, Read a) => Read (These a b) Source #
Methods readsPrec :: Int -> ReadS (These a b) # readList :: ReadS [These a b] # readPrec :: ReadPrec (These a b) # readListPrec :: ReadPrec [These a b] #
(Show b, Show a) => Show (These a b) Source #
Methods showsPrec :: Int -> These a b -> ShowS # show :: These a b -> String # showList :: [These a b] -> ShowS #
Generic (These a b) Source #
Associated Types type Rep (These a b) :: * -> * # Methods from :: These a b -> Rep (These a b) x # to :: Rep (These a b) x -> These a b #
(Semigroup a, Semigroup b) => Semigroup (These a b) Source #
Methods (<>) :: These a b -> These a b -> These a b # sconcat :: NonEmpty (These a b) -> These a b # stimes :: Integral b => b -> These a b -> These a b #
(Function a, Function b) => Function (These a b) Source #
Methods function :: (These a b -> b) -> These a b :-> b #
(Arbitrary a, Arbitrary b) => Arbitrary (These a b) Source #
Methods arbitrary :: Gen (These a b) # shrink :: These a b -> [These a b] #
(CoArbitrary a, CoArbitrary b) => CoArbitrary (These a b) Source #
Methods coarbitrary :: These a b -> Gen b -> Gen b #
(Hashable a, Hashable b) => Hashable (These a b) Source #
Methods hashWithSalt :: Int -> These a b -> Int # hash :: These a b -> Int #
(ToJSON a, ToJSON b) => ToJSON (These a b) Source #
Methods toJSON :: These a b -> Value # toEncoding :: These a b -> Encoding # toJSONList :: [These a b] -> Value # toEncodingList :: [These a b] -> Encoding #
(FromJSON a, FromJSON b) => FromJSON (These a b) Source #
Methods parseJSON :: Value -> Parser (These a b) # parseJSONList :: Value -> Parser [These a b] #
(Binary a, Binary b) => Binary (These a b) Source #
Methods put :: These a b -> Put # get :: Get (These a b) # putList :: [These a b] -> Put #
(NFData a, NFData b) => NFData (These a b) Source #
Methods rnf :: These a b -> () #
type Rep (These a b) Source #
type Rep (These a b) = D1 (MetaData "These" "Data.These" "these-0.7.4-BfJT52qC3GRHqSEEsntQt9" False) ((:+:) (C1 (MetaCons "This" PrefixI False) (S1 (MetaSel (Nothing Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 a))) ((:+:) (C1 (MetaCons "That" PrefixI False) (S1 (MetaSel (Nothing Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 b))) (C1 (MetaCons "These" PrefixI False) ((:*:) (S1 (MetaSel (Nothing Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 a)) (S1 (MetaSel (Nothing Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 b))))))

Functions to get rid of `These`

these :: (a -> c) -> (b -> c) -> (a -> b -> c) -> These a b -> c Source #

Case analysis for the These type.

fromThese :: a -> b -> These a b -> (a, b) Source #

Takes two default values and produces a tuple.

mergeThese :: (a -> a -> a) -> These a a -> a Source #

Coalesce with the provided operation.

mergeTheseWith :: (a -> c) -> (b -> c) -> (c -> c -> c) -> These a b -> c Source #

BiMap and coalesce results with the provided operation.

Traversals

here :: Applicative f => (a -> f b) -> These a t -> f (These b t) Source #

A Traversal of the first half of a These, suitable for use with Control.Lens.

there :: Applicative f => (a -> f b) -> These t a -> f (These t b) Source #

A Traversal of the second half of a These, suitable for use with Control.Lens.

Prisms

_This :: (Choice p, Applicative f) => p a (f a) -> p (These a b) (f (These a b)) Source #

A Prism selecting the This constructor.

_That :: (Choice p, Applicative f) => p b (f b) -> p (These a b) (f (These a b)) Source #

A Prism selecting the That constructor.

_These :: (Choice p, Applicative f) => p (a, b) (f (a, b)) -> p (These a b) (f (These a b)) Source #

A Prism selecting the These constructor. These names are ridiculous!

Case selections

justThis :: These a b -> Maybe a Source #

justThis = preview _This

justThat :: These a b -> Maybe b Source #

justThat = preview _That

justThese :: These a b -> Maybe (a, b) Source #

justThese = preview _These

catThis :: [These a b] -> [a] Source #

Select all This constructors from a list.

catThat :: [These a b] -> [b] Source #

Select all That constructors from a list.

catThese :: [These a b] -> [(a, b)] Source #

Select all These constructors from a list.

partitionThese :: [These a b] -> ([(a, b)], ([a], [b])) Source #

Select each constructor and partition them into separate lists.

Case predicates

isThis :: These a b -> Bool Source #

isThis = isJust . justThis

isThat :: These a b -> Bool Source #

isThat = isJust . justThat

isThese :: These a b -> Bool Source #

isThese = isJust . justThese

Map operations

mapThese :: (a -> c) -> (b -> d) -> These a b -> These c d Source #

Bifunctor map.

mapThis :: (a -> c) -> These a b -> These c b Source #

mapThis = over here

mapThat :: (b -> d) -> These a b -> These a d Source #

mapThat = over there

For zipping and unzipping of structures with These values, see Data.Align.