Copyright	[2018..2020] The Accelerate Team
License	BSD3
Maintainer	Trevor L. McDonell <trevor.mcdonell@gmail.com>
Stability	experimental
Portability	non-portable (GHC extensions)
Safe Haskell	Safe-Inferred
Language	Haskell2010

Data.Array.Accelerate.Data.Either

Contents

Orphan instances

Description

Since: 1.2.0.0

Synopsis

data Either a b
- = Left a
- | Right b
pattern Left_ :: forall a b. (HasCallStack, Elt a, Elt b) => Exp a -> Exp (Either a b)
pattern Right_ :: forall a b. (HasCallStack, Elt a, Elt b) => Exp b -> Exp (Either a b)
either :: (Elt a, Elt b, Elt c) => (Exp a -> Exp c) -> (Exp b -> Exp c) -> Exp (Either a b) -> Exp c
isLeft :: (Elt a, Elt b) => Exp (Either a b) -> Exp Bool
isRight :: (Elt a, Elt b) => Exp (Either a b) -> Exp Bool
fromLeft :: (Elt a, Elt b) => Exp (Either a b) -> Exp a
fromRight :: (Elt a, Elt b) => Exp (Either a b) -> Exp b
lefts :: (Shape sh, Slice sh, Elt a, Elt b) => Acc (Array (sh :. Int) (Either a b)) -> Acc (Vector a, Array sh Int)
rights :: (Shape sh, Slice sh, Elt a, Elt b) => Acc (Array (sh :. Int) (Either a b)) -> Acc (Vector b, Array sh Int)

Documentation

data Either a b #

The Either type represents values with two possibilities: a value of type Either a b is either Left a or Right b.

The Either type is sometimes used to represent a value which is either correct or an error; by convention, the Left constructor is used to hold an error value and the Right constructor is used to hold a correct value (mnemonic: "right" also means "correct").

Examples

Expand

The type Either String Int is the type of values which can be either a String or an Int. The Left constructor can be used only on Strings, and the Right constructor can be used only on Ints:

>>> let s = Left "foo" :: Either String Int
>>> s
Left "foo"
>>> let n = Right 3 :: Either String Int
>>> n
Right 3
>>> :type s
s :: Either String Int
>>> :type n
n :: Either String Int

The fmap from our Functor instance will ignore Left values, but will apply the supplied function to values contained in a Right:

>>> let s = Left "foo" :: Either String Int
>>> let n = Right 3 :: Either String Int
>>> fmap (*2) s
Left "foo"
>>> fmap (*2) n
Right 6

The Monad instance for Either allows us to chain together multiple actions which may fail, and fail overall if any of the individual steps failed. First we'll write a function that can either parse an Int from a Char, or fail.

>>> import Data.Char ( digitToInt, isDigit )
>>> :{
    let parseEither :: Char -> Either String Int
        parseEither c
          | isDigit c = Right (digitToInt c)
          | otherwise = Left "parse error"
>>> :}

The following should work, since both '1' and '2' can be parsed as Ints.

>>> :{
    let parseMultiple :: Either String Int
        parseMultiple = do
          x <- parseEither '1'
          y <- parseEither '2'
          return (x + y)
>>> :}

>>> parseMultiple
Right 3

But the following should fail overall, since the first operation where we attempt to parse 'm' as an Int will fail:

>>> :{
    let parseMultiple :: Either String Int
        parseMultiple = do
          x <- parseEither 'm'
          y <- parseEither '2'
          return (x + y)
>>> :}

>>> parseMultiple
Left "parse error"

Constructors

Left a
Right b

Instances

Instances details

Eq2 Either	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Classes Methods liftEq2 :: (a -> b -> Bool) -> (c -> d -> Bool) -> Either a c -> Either b d -> Bool #
Ord2 Either	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Classes Methods liftCompare2 :: (a -> b -> Ordering) -> (c -> d -> Ordering) -> Either a c -> Either b d -> Ordering #
Read2 Either	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Classes Methods liftReadsPrec2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> Int -> ReadS (Either a b) # liftReadList2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> ReadS [Either a b] # liftReadPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec (Either a b) # liftReadListPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec [Either a b] #
Show2 Either	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Classes Methods liftShowsPrec2 :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> (Int -> b -> ShowS) -> ([b] -> ShowS) -> Int -> Either a b -> ShowS # liftShowList2 :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> (Int -> b -> ShowS) -> ([b] -> ShowS) -> [Either a b] -> ShowS #
NFData2 Either	Since: deepseq-1.4.3.0
Instance details Defined in Control.DeepSeq Methods liftRnf2 :: (a -> ()) -> (b -> ()) -> Either a b -> () #
Hashable2 Either
Instance details Defined in Data.Hashable.Class Methods liftHashWithSalt2 :: (Int -> a -> Int) -> (Int -> b -> Int) -> Int -> Either a b -> Int Source #
Generic1 (Either a :: Type -> Type)
Instance details Defined in GHC.Generics Associated Types type Rep1 (Either a) :: k -> Type # Methods from1 :: forall (a0 :: k). Either a a0 -> Rep1 (Either a) a0 # to1 :: forall (a0 :: k). Rep1 (Either a) a0 -> Either a a0 #
(Lift Exp a, Lift Exp b, Elt (Plain a), Elt (Plain b)) => Lift Exp (Either a b) Source #
Instance details Defined in Data.Array.Accelerate.Data.Either Associated Types type Plain (Either a b) Source # Methods lift :: Either a b -> Exp (Plain (Either a b)) Source #
(Lift a, Lift b) => Lift (Either a b :: Type)
Instance details Defined in Language.Haskell.TH.Syntax Methods lift :: Quote m => Either a b -> m Exp # liftTyped :: forall (m :: Type -> Type). Quote m => Either a b -> Code m (Either a b) #
Elt a => Monad (Either a) Source #
Instance details Defined in Data.Array.Accelerate.Data.Either Methods (>>=) :: (Elt a0, Elt b, Elt (Either a a0), Elt (Either a b)) => Exp (Either a a0) -> (Exp a0 -> Exp (Either a b)) -> Exp (Either a b) Source # return :: (Elt a0, Elt (Either a a0)) => Exp a0 -> Exp (Either a a0) Source #
Elt a => Functor (Either a) Source #
Instance details Defined in Data.Array.Accelerate.Data.Either Methods fmap :: (Elt a0, Elt b, Elt (Either a a0), Elt (Either a b)) => (Exp a0 -> Exp b) -> Exp (Either a a0) -> Exp (Either a b) Source # (<$) :: (Elt a0, Elt b, Elt (Either a a0), Elt (Either a b)) => Exp a0 -> Exp (Either a b) -> Exp (Either a a0) Source #
MonadFix (Either e)	Since: base-4.3.0.0
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> Either e a) -> Either e a #
Foldable (Either a)	Since: base-4.7.0.0
Instance details Defined in Data.Foldable Methods fold :: Monoid m => Either a m -> m # foldMap :: Monoid m => (a0 -> m) -> Either a a0 -> m # foldMap' :: Monoid m => (a0 -> m) -> Either a a0 -> m # foldr :: (a0 -> b -> b) -> b -> Either a a0 -> b # foldr' :: (a0 -> b -> b) -> b -> Either a a0 -> b # foldl :: (b -> a0 -> b) -> b -> Either a a0 -> b # foldl' :: (b -> a0 -> b) -> b -> Either a a0 -> b # foldr1 :: (a0 -> a0 -> a0) -> Either a a0 -> a0 # foldl1 :: (a0 -> a0 -> a0) -> Either a a0 -> a0 # toList :: Either a a0 -> [a0] # null :: Either a a0 -> Bool # length :: Either a a0 -> Int # elem :: Eq a0 => a0 -> Either a a0 -> Bool # maximum :: Ord a0 => Either a a0 -> a0 # minimum :: Ord a0 => Either a a0 -> a0 # sum :: Num a0 => Either a a0 -> a0 # product :: Num a0 => Either a a0 -> a0 #
Eq a => Eq1 (Either a)	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Classes Methods liftEq :: (a0 -> b -> Bool) -> Either a a0 -> Either a b -> Bool #
Ord a => Ord1 (Either a)	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Classes Methods liftCompare :: (a0 -> b -> Ordering) -> Either a a0 -> Either a b -> Ordering #
Read a => Read1 (Either a)	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Classes Methods liftReadsPrec :: (Int -> ReadS a0) -> ReadS [a0] -> Int -> ReadS (Either a a0) # liftReadList :: (Int -> ReadS a0) -> ReadS [a0] -> ReadS [Either a a0] # liftReadPrec :: ReadPrec a0 -> ReadPrec [a0] -> ReadPrec (Either a a0) # liftReadListPrec :: ReadPrec a0 -> ReadPrec [a0] -> ReadPrec [Either a a0] #
Show a => Show1 (Either a)	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Classes Methods liftShowsPrec :: (Int -> a0 -> ShowS) -> ([a0] -> ShowS) -> Int -> Either a a0 -> ShowS # liftShowList :: (Int -> a0 -> ShowS) -> ([a0] -> ShowS) -> [Either a a0] -> ShowS #
Traversable (Either a)	Since: base-4.7.0.0
Instance details Defined in Data.Traversable Methods traverse :: Applicative f => (a0 -> f b) -> Either a a0 -> f (Either a b) # sequenceA :: Applicative f => Either a (f a0) -> f (Either a a0) # mapM :: Monad m => (a0 -> m b) -> Either a a0 -> m (Either a b) # sequence :: Monad m => Either a (m a0) -> m (Either a a0) #
Applicative (Either e)	Since: base-3.0
Instance details Defined in Data.Either Methods pure :: a -> Either e a # (<>) :: Either e (a -> b) -> Either e a -> Either e b # liftA2 :: (a -> b -> c) -> Either e a -> Either e b -> Either e c # (>) :: Either e a -> Either e b -> Either e b # (<*) :: Either e a -> Either e b -> Either e a #
Functor (Either a)	Since: base-3.0
Instance details Defined in Data.Either Methods fmap :: (a0 -> b) -> Either a a0 -> Either a b # (<$) :: a0 -> Either a b -> Either a a0 #
Monad (Either e)	Since: base-4.4.0.0
Instance details Defined in Data.Either Methods (>>=) :: Either e a -> (a -> Either e b) -> Either e b # (>>) :: Either e a -> Either e b -> Either e b # return :: a -> Either e a #
(Elt a, Elt b) => Semigroup (Exp (Either a b)) Source #
Instance details Defined in Data.Array.Accelerate.Data.Either Methods (<>) :: Exp (Either a b) -> Exp (Either a b) -> Exp (Either a b) # sconcat :: NonEmpty (Exp (Either a b)) -> Exp (Either a b) # stimes :: Integral b0 => b0 -> Exp (Either a b) -> Exp (Either a b) #
NFData a => NFData1 (Either a)	Since: deepseq-1.4.3.0
Instance details Defined in Control.DeepSeq Methods liftRnf :: (a0 -> ()) -> Either a a0 -> () #
e ~ SomeException => MonadCatch (Either e)	Since: exceptions-0.8.3
Instance details Defined in Control.Monad.Catch Methods catch :: Exception e0 => Either e a -> (e0 -> Either e a) -> Either e a #
e ~ SomeException => MonadMask (Either e)	Since: exceptions-0.8.3
Instance details Defined in Control.Monad.Catch Methods mask :: ((forall a. Either e a -> Either e a) -> Either e b) -> Either e b # uninterruptibleMask :: ((forall a. Either e a -> Either e a) -> Either e b) -> Either e b # generalBracket :: Either e a -> (a -> ExitCase b -> Either e c) -> (a -> Either e b) -> Either e (b, c) #
e ~ SomeException => MonadThrow (Either e)
Instance details Defined in Control.Monad.Catch Methods throwM :: Exception e0 => e0 -> Either e a #
Hashable a => Hashable1 (Either a)
Instance details Defined in Data.Hashable.Class Methods liftHashWithSalt :: (Int -> a0 -> Int) -> Int -> Either a a0 -> Int Source #
MonadBaseControl (Either e) (Either e)
Instance details Defined in Control.Monad.Trans.Control Associated Types type StM (Either e) a Source # Methods liftBaseWith :: (RunInBase (Either e) (Either e) -> Either e a) -> Either e a Source # restoreM :: StM (Either e) a -> Either e a Source #
(Eq a, Eq b) => Eq (Either a b) Source #
Instance details Defined in Data.Array.Accelerate.Data.Either Methods (==) :: Exp (Either a b) -> Exp (Either a b) -> Exp Bool Source # (/=) :: Exp (Either a b) -> Exp (Either a b) -> Exp Bool Source #
(Ord a, Ord b) => Ord (Either a b) Source #
Instance details Defined in Data.Array.Accelerate.Data.Either Methods (<) :: Exp (Either a b) -> Exp (Either a b) -> Exp Bool Source # (>) :: Exp (Either a b) -> Exp (Either a b) -> Exp Bool Source # (<=) :: Exp (Either a b) -> Exp (Either a b) -> Exp Bool Source # (>=) :: Exp (Either a b) -> Exp (Either a b) -> Exp Bool Source # min :: Exp (Either a b) -> Exp (Either a b) -> Exp (Either a b) Source # max :: Exp (Either a b) -> Exp (Either a b) -> Exp (Either a b) Source # compare :: Exp (Either a b) -> Exp (Either a b) -> Exp Ordering Source #
(Elt a, Elt b) => Elt (Either a b) Source #
Instance details Defined in Data.Array.Accelerate.Sugar.Elt Associated Types type EltR (Either a b) Methods eltR :: TypeR (EltR (Either a b)) tagsR :: [TagR (EltR (Either a b))] fromElt :: Either a b -> EltR (Either a b) toElt :: EltR (Either a b) -> Either a b
(Data a, Data b) => Data (Either a b)	Since: base-4.0.0.0
Instance details Defined in Data.Data Methods gfoldl :: (forall d b0. Data d => c (d -> b0) -> d -> c b0) -> (forall g. g -> c g) -> Either a b -> c (Either a b) # gunfold :: (forall b0 r. Data b0 => c (b0 -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Either a b) # toConstr :: Either a b -> Constr # dataTypeOf :: Either a b -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Either a b)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Either a b)) # gmapT :: (forall b0. Data b0 => b0 -> b0) -> Either a b -> Either a b # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Either a b -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Either a b -> r # gmapQ :: (forall d. Data d => d -> u) -> Either a b -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Either a b -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Either a b -> m (Either a b) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Either a b -> m (Either a b) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Either a b -> m (Either a b) #
Semigroup (Either a b)	Since: base-4.9.0.0
Instance details Defined in Data.Either Methods (<>) :: Either a b -> Either a b -> Either a b # sconcat :: NonEmpty (Either a b) -> Either a b # stimes :: Integral b0 => b0 -> Either a b -> Either a b #
Generic (Either a b)
Instance details Defined in GHC.Generics Associated Types type Rep (Either a b) :: Type -> Type # Methods from :: Either a b -> Rep (Either a b) x # to :: Rep (Either a b) x -> Either a b #
(Read a, Read b) => Read (Either a b)	Since: base-3.0
Instance details Defined in Data.Either Methods readsPrec :: Int -> ReadS (Either a b) # readList :: ReadS [Either a b] # readPrec :: ReadPrec (Either a b) # readListPrec :: ReadPrec [Either a b] #
(Show a, Show b) => Show (Either a b)	Since: base-3.0
Instance details Defined in Data.Either Methods showsPrec :: Int -> Either a b -> ShowS # show :: Either a b -> String # showList :: [Either a b] -> ShowS #
(NFData a, NFData b) => NFData (Either a b)
Instance details Defined in Control.DeepSeq Methods rnf :: Either a b -> () #
(Eq a, Eq b) => Eq (Either a b)	Since: base-2.1
Instance details Defined in Data.Either Methods (==) :: Either a b -> Either a b -> Bool # (/=) :: Either a b -> Either a b -> Bool #
(Ord a, Ord b) => Ord (Either a b)	Since: base-2.1
Instance details Defined in Data.Either Methods compare :: Either a b -> Either a b -> Ordering # (<) :: Either a b -> Either a b -> Bool # (<=) :: Either a b -> Either a b -> Bool # (>) :: Either a b -> Either a b -> Bool # (>=) :: Either a b -> Either a b -> Bool # max :: Either a b -> Either a b -> Either a b # min :: Either a b -> Either a b -> Either a b #
(Hashable a, Hashable b) => Hashable (Either a b)
Instance details Defined in Data.Hashable.Class Methods hashWithSalt :: Int -> Either a b -> Int Source # hash :: Either a b -> Int Source #
(a ~ a', b ~ b') => Each (Either a a') (Either b b') a b	Since: microlens-0.4.11
Instance details Defined in Lens.Micro.Internal Methods each :: Traversal (Either a a') (Either b b') a b Source #
type Rep1 (Either a :: Type -> Type)	Since: base-4.6.0.0
Instance details Defined in GHC.Generics type Rep1 (Either a :: Type -> Type) = D1 ('MetaData "Either" "Data.Either" "base" 'False) (C1 ('MetaCons "Left" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 a)) :+: C1 ('MetaCons "Right" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) Par1))
type StM (Either e) a
Instance details Defined in Control.Monad.Trans.Control type StM (Either e) a = a
type Plain (Either a b) Source #
Instance details Defined in Data.Array.Accelerate.Data.Either type Plain (Either a b) = Either (Plain a) (Plain b)
type Rep (Either a b)	Since: base-4.6.0.0
Instance details Defined in GHC.Generics type Rep (Either a b) = D1 ('MetaData "Either" "Data.Either" "base" 'False) (C1 ('MetaCons "Left" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 a)) :+: C1 ('MetaCons "Right" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 b)))

pattern Left_ :: forall a b. (HasCallStack, Elt a, Elt b) => Exp a -> Exp (Either a b) Source #

pattern Right_ :: forall a b. (HasCallStack, Elt a, Elt b) => Exp b -> Exp (Either a b) Source #

either :: (Elt a, Elt b, Elt c) => (Exp a -> Exp c) -> (Exp b -> Exp c) -> Exp (Either a b) -> Exp c Source #

The either function performs case analysis on the Either type. If the value is Left a, apply the first function to a; if it is Right b, apply the second function to b.

isLeft :: (Elt a, Elt b) => Exp (Either a b) -> Exp Bool Source #

Return True if the argument is a Left-value

isRight :: (Elt a, Elt b) => Exp (Either a b) -> Exp Bool Source #

Return True if the argument is a Right-value

fromLeft :: (Elt a, Elt b) => Exp (Either a b) -> Exp a Source #

The fromLeft function extracts the element out of the Left constructor. If the argument was actually Right, you will get an undefined value instead.

fromRight :: (Elt a, Elt b) => Exp (Either a b) -> Exp b Source #

The fromRight function extracts the element out of the Right constructor. If the argument was actually Left, you will get an undefined value instead.

lefts :: (Shape sh, Slice sh, Elt a, Elt b) => Acc (Array (sh :. Int) (Either a b)) -> Acc (Vector a, Array sh Int) Source #

Extract from the array of Either all of the Left elements, together with a segment descriptor indicating how many elements along each dimension were returned.

rights :: (Shape sh, Slice sh, Elt a, Elt b) => Acc (Array (sh :. Int) (Either a b)) -> Acc (Vector b, Array sh Int) Source #

Extract from the array of Either all of the Right elements, together with a segment descriptor indicating how many elements along each dimension were returned.

Orphan instances

(Lift Exp a, Lift Exp b, Elt (Plain a), Elt (Plain b)) => Lift Exp (Either a b) Source #
Instance details Associated Types type Plain (Either a b) Source # Methods lift :: Either a b -> Exp (Plain (Either a b)) Source #
Elt a => Monad (Either a) Source #
Instance details Methods (>>=) :: (Elt a0, Elt b, Elt (Either a a0), Elt (Either a b)) => Exp (Either a a0) -> (Exp a0 -> Exp (Either a b)) -> Exp (Either a b) Source # return :: (Elt a0, Elt (Either a a0)) => Exp a0 -> Exp (Either a a0) Source #
Elt a => Functor (Either a) Source #
Instance details Methods fmap :: (Elt a0, Elt b, Elt (Either a a0), Elt (Either a b)) => (Exp a0 -> Exp b) -> Exp (Either a a0) -> Exp (Either a b) Source # (<$) :: (Elt a0, Elt b, Elt (Either a a0), Elt (Either a b)) => Exp a0 -> Exp (Either a b) -> Exp (Either a a0) Source #
(Elt a, Elt b) => Semigroup (Exp (Either a b)) Source #
Instance details Methods (<>) :: Exp (Either a b) -> Exp (Either a b) -> Exp (Either a b) # sconcat :: NonEmpty (Exp (Either a b)) -> Exp (Either a b) # stimes :: Integral b0 => b0 -> Exp (Either a b) -> Exp (Either a b) #
(Eq a, Eq b) => Eq (Either a b) Source #
Instance details Methods (==) :: Exp (Either a b) -> Exp (Either a b) -> Exp Bool Source # (/=) :: Exp (Either a b) -> Exp (Either a b) -> Exp Bool Source #
(Ord a, Ord b) => Ord (Either a b) Source #
Instance details Methods (<) :: Exp (Either a b) -> Exp (Either a b) -> Exp Bool Source # (>) :: Exp (Either a b) -> Exp (Either a b) -> Exp Bool Source # (<=) :: Exp (Either a b) -> Exp (Either a b) -> Exp Bool Source # (>=) :: Exp (Either a b) -> Exp (Either a b) -> Exp Bool Source # min :: Exp (Either a b) -> Exp (Either a b) -> Exp (Either a b) Source # max :: Exp (Either a b) -> Exp (Either a b) -> Exp (Either a b) Source # compare :: Exp (Either a b) -> Exp (Either a b) -> Exp Ordering Source #