Copyright	(c) 2017 Daniel Mendler 2006-2007 Roman Leshchinskiy
License	BSD-style (see the file LICENSE)
Maintainer	Daniel Mendler <mail@daniel-mendler.de>
Stability	experimental
Portability	portable
Safe Haskell	Safe
Language	Haskell2010

Data.Strict.Maybe

Contents

Orphan instances

Description

Strict Maybe.

Same as the standard Haskell Maybe, but Just _|_ = _|_

Note that strict Maybe is not a monad since return _|_ >>= f = _|_ which is not necessarily the same as f _|_.

Synopsis

Documentation

data Maybe a Source #

The type of strict optional values.

Constructors

Nothing
Just !a

Instances

Functor Maybe Source #
Methods fmap :: (a -> b) -> Maybe a -> Maybe b # (<$) :: a -> Maybe b -> Maybe a #
Foldable Maybe Source #
Methods fold :: Monoid m => Maybe m -> m # foldMap :: Monoid m => (a -> m) -> Maybe a -> m # foldr :: (a -> b -> b) -> b -> Maybe a -> b # foldr' :: (a -> b -> b) -> b -> Maybe a -> b # foldl :: (b -> a -> b) -> b -> Maybe a -> b # foldl' :: (b -> a -> b) -> b -> Maybe a -> b # foldr1 :: (a -> a -> a) -> Maybe a -> a # foldl1 :: (a -> a -> a) -> Maybe a -> a # toList :: Maybe a -> [a] # null :: Maybe a -> Bool # length :: Maybe a -> Int # elem :: Eq a => a -> Maybe a -> Bool # maximum :: Ord a => Maybe a -> a # minimum :: Ord a => Maybe a -> a # sum :: Num a => Maybe a -> a # product :: Num a => Maybe a -> a #
Traversable Maybe Source #
Methods traverse :: Applicative f => (a -> f b) -> Maybe a -> f (Maybe b) # sequenceA :: Applicative f => Maybe (f a) -> f (Maybe a) # mapM :: Monad m => (a -> m b) -> Maybe a -> m (Maybe b) # sequence :: Monad m => Maybe (m a) -> m (Maybe a) #
Generic1 Maybe Source #
Associated Types type Rep1 (Maybe :: * -> ) :: -> * # Methods from1 :: Maybe a -> Rep1 Maybe a # to1 :: Rep1 Maybe a -> Maybe a #
Eq a => Eq (Maybe a) Source #
Methods (==) :: Maybe a -> Maybe a -> Bool # (/=) :: Maybe a -> Maybe a -> Bool #
Data a => Data (Maybe a) Source #
Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Maybe a -> c (Maybe a) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Maybe a) # toConstr :: Maybe a -> Constr # dataTypeOf :: Maybe a -> DataType # dataCast1 :: Typeable (* -> ) t => (forall d. Data d => c (t d)) -> Maybe (c (Maybe a)) # dataCast2 :: Typeable ( -> * -> *) t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Maybe a)) # gmapT :: (forall b. Data b => b -> b) -> Maybe a -> Maybe a # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Maybe a -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Maybe a -> r # gmapQ :: (forall d. Data d => d -> u) -> Maybe a -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Maybe a -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a) #
Ord a => Ord (Maybe a) Source #
Methods compare :: Maybe a -> Maybe a -> Ordering # (<) :: Maybe a -> Maybe a -> Bool # (<=) :: Maybe a -> Maybe a -> Bool # (>) :: Maybe a -> Maybe a -> Bool # (>=) :: Maybe a -> Maybe a -> Bool # max :: Maybe a -> Maybe a -> Maybe a # min :: Maybe a -> Maybe a -> Maybe a #
Read a => Read (Maybe a) Source #
Methods readsPrec :: Int -> ReadS (Maybe a) # readList :: ReadS [Maybe a] # readPrec :: ReadPrec (Maybe a) # readListPrec :: ReadPrec [Maybe a] #
Show a => Show (Maybe a) Source #
Methods showsPrec :: Int -> Maybe a -> ShowS # show :: Maybe a -> String # showList :: [Maybe a] -> ShowS #
Generic (Maybe a) Source #
Associated Types type Rep (Maybe a) :: * -> * # Methods from :: Maybe a -> Rep (Maybe a) x # to :: Rep (Maybe a) x -> Maybe a #
Semigroup a => Semigroup (Maybe a) Source #
Methods (<>) :: Maybe a -> Maybe a -> Maybe a # sconcat :: NonEmpty (Maybe a) -> Maybe a # stimes :: Integral b => b -> Maybe a -> Maybe a #
Monoid a => Monoid (Maybe a) Source #
Methods mempty :: Maybe a # mappend :: Maybe a -> Maybe a -> Maybe a # mconcat :: [Maybe a] -> Maybe a #
type Rep1 Maybe Source #
type Rep1 Maybe = D1 (MetaData "Maybe" "Data.Strict.Maybe" "strict-base-0.4.0.0-1k3wDu59CS22iu6yIZo2Dn" False) ((:+:) (C1 (MetaCons "Nothing" PrefixI False) U1) (C1 (MetaCons "Just" PrefixI False) (S1 (MetaSel (Nothing Symbol) NoSourceUnpackedness SourceStrict DecidedStrict) Par1)))
type Rep (Maybe a) Source #
type Rep (Maybe a) = D1 (MetaData "Maybe" "Data.Strict.Maybe" "strict-base-0.4.0.0-1k3wDu59CS22iu6yIZo2Dn" False) ((:+:) (C1 (MetaCons "Nothing" PrefixI False) U1) (C1 (MetaCons "Just" PrefixI False) (S1 (MetaSel (Nothing Symbol) NoSourceUnpackedness SourceStrict DecidedStrict) (Rec0 a))))

isJust :: Maybe a -> Bool Source #

Yields True iff the argument is of the form Just _.

isNothing :: Maybe a -> Bool Source #

Yields True iff the argument is Nothing.

fromMaybe :: a -> Maybe a -> a Source #

Given a default value and a Maybe, yield the default value if the Maybe argument is Nothing and extract the value out of the Just otherwise.

maybe :: b -> (a -> b) -> Maybe a -> b Source #

Given a default value, a function and a Maybe value, yields the default value if the Maybe value is Nothing and applies the function to the value stored in the Just otherwise.

listToMaybe :: [a] -> Maybe a Source #

Analogous to listToMaybe in Data.Maybe.

maybeToList :: Maybe a -> [a] Source #

Analogous to maybeToList in Data.Maybe.

mapMaybe :: (a -> Maybe b) -> [a] -> [b] Source #

Analogous to mapMaybe in Data.Maybe.

catMaybes :: [Maybe a] -> [a] Source #

Analogous to catMaybes in Data.Maybe.

Orphan instances

IsStrict (Maybe a) (Maybe a) Source #
Methods fromStrict :: Maybe a -> Maybe a Source # toStrict :: Maybe a -> Maybe a Source #