Safe Haskell	None
Language	Haskell2010

PlutusTx.Maybe

Synopsis

data Maybe a
- = Nothing
- | Just a
isJust :: Maybe a -> Bool
isNothing :: Maybe a -> Bool
maybe :: b -> (a -> b) -> Maybe a -> b
fromMaybe :: a -> Maybe a -> a
mapMaybe :: (a -> Maybe b) -> [a] -> [b]

Documentation

data Maybe a Source #

The Maybe type encapsulates an optional value. A value of type Maybe a either contains a value of type a (represented as Just a), or it is empty (represented as Nothing). Using Maybe is a good way to deal with errors or exceptional cases without resorting to drastic measures such as error.

The Maybe type is also a monad. It is a simple kind of error monad, where all errors are represented by Nothing. A richer error monad can be built using the Either type.

Constructors

Nothing
Just a

Instances

Instances details

Monad Maybe	Since: base-2.1
Instance details Defined in GHC.Base Methods (>>=) :: Maybe a -> (a -> Maybe b) -> Maybe b Source # (>>) :: Maybe a -> Maybe b -> Maybe b Source # return :: a -> Maybe a Source #
Functor Maybe	Since: base-2.1
Instance details Defined in GHC.Base Methods fmap :: (a -> b) -> Maybe a -> Maybe b Source # (<$) :: a -> Maybe b -> Maybe a Source #
MonadFix Maybe	Since: base-2.1
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> Maybe a) -> Maybe a Source #
MonadFail Maybe	Since: base-4.9.0.0
Instance details Defined in Control.Monad.Fail Methods fail :: String -> Maybe a Source #
Applicative Maybe	Since: base-2.1
Instance details Defined in GHC.Base Methods pure :: a -> Maybe a Source # (<>) :: Maybe (a -> b) -> Maybe a -> Maybe b Source # liftA2 :: (a -> b -> c) -> Maybe a -> Maybe b -> Maybe c Source # (>) :: Maybe a -> Maybe b -> Maybe b Source # (<*) :: Maybe a -> Maybe b -> Maybe a Source #
Foldable Maybe	Since: base-2.1
Instance details Defined in Data.Foldable Methods fold :: Monoid m => Maybe m -> m Source # foldMap :: Monoid m => (a -> m) -> Maybe a -> m Source # foldMap' :: Monoid m => (a -> m) -> Maybe a -> m Source # foldr :: (a -> b -> b) -> b -> Maybe a -> b Source # foldr' :: (a -> b -> b) -> b -> Maybe a -> b Source # foldl :: (b -> a -> b) -> b -> Maybe a -> b Source # foldl' :: (b -> a -> b) -> b -> Maybe a -> b Source # foldr1 :: (a -> a -> a) -> Maybe a -> a Source # foldl1 :: (a -> a -> a) -> Maybe a -> a Source # toList :: Maybe a -> [a] Source # null :: Maybe a -> Bool Source # length :: Maybe a -> Int Source # elem :: Eq a => a -> Maybe a -> Bool Source # maximum :: Ord a => Maybe a -> a Source # minimum :: Ord a => Maybe a -> a Source # sum :: Num a => Maybe a -> a Source # product :: Num a => Maybe a -> a Source #
Traversable Maybe	Since: base-2.1
Instance details Defined in Data.Traversable Methods traverse :: Applicative f => (a -> f b) -> Maybe a -> f (Maybe b) Source # sequenceA :: Applicative f => Maybe (f a) -> f (Maybe a) Source # mapM :: Monad m => (a -> m b) -> Maybe a -> m (Maybe b) Source # sequence :: Monad m => Maybe (m a) -> m (Maybe a) Source #
Eq1 Maybe	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Classes Methods liftEq :: (a -> b -> Bool) -> Maybe a -> Maybe b -> Bool Source #
Ord1 Maybe	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Classes Methods liftCompare :: (a -> b -> Ordering) -> Maybe a -> Maybe b -> Ordering Source #
Read1 Maybe	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Classes Methods liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Maybe a) Source # liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [Maybe a] Source # liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (Maybe a) Source # liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [Maybe a] Source #
Show1 Maybe	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Classes Methods liftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> Maybe a -> ShowS Source # liftShowList :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> [Maybe a] -> ShowS Source #
Alternative Maybe	Since: base-2.1
Instance details Defined in GHC.Base Methods empty :: Maybe a Source # (<\|>) :: Maybe a -> Maybe a -> Maybe a Source # some :: Maybe a -> Maybe [a] Source # many :: Maybe a -> Maybe [a] Source #
MonadPlus Maybe	Since: base-2.1
Instance details Defined in GHC.Base Methods mzero :: Maybe a Source # mplus :: Maybe a -> Maybe a -> Maybe a Source #
NFData1 Maybe	Since: deepseq-1.4.3.0
Instance details Defined in Control.DeepSeq Methods liftRnf :: (a -> ()) -> Maybe a -> () Source #
FromJSON1 Maybe
Instance details Defined in Data.Aeson.Types.FromJSON Methods liftParseJSON :: (Value -> Parser a) -> (Value -> Parser [a]) -> Value -> Parser (Maybe a) liftParseJSONList :: (Value -> Parser a) -> (Value -> Parser [a]) -> Value -> Parser [Maybe a]
ToJSON1 Maybe
Instance details Defined in Data.Aeson.Types.ToJSON Methods liftToJSON :: (a -> Value) -> ([a] -> Value) -> Maybe a -> Value liftToJSONList :: (a -> Value) -> ([a] -> Value) -> [Maybe a] -> Value liftToEncoding :: (a -> Encoding) -> ([a] -> Encoding) -> Maybe a -> Encoding liftToEncodingList :: (a -> Encoding) -> ([a] -> Encoding) -> [Maybe a] -> Encoding
Hashable1 Maybe
Instance details Defined in Data.Hashable.Class Methods liftHashWithSalt :: (Int -> a -> Int) -> Int -> Maybe a -> Int
Functor Maybe Source #
Instance details Defined in PlutusTx.Functor Methods fmap :: (a -> b) -> Maybe a -> Maybe b Source #
MonadFailure Maybe
Instance details Defined in Basement.Monad Associated Types type Failure Maybe Methods mFail :: Failure Maybe -> Maybe ()
Applicative Maybe Source #
Instance details Defined in PlutusTx.Applicative Methods pure :: a -> Maybe a Source # (<*>) :: Maybe (a -> b) -> Maybe a -> Maybe b Source #
Foldable Maybe Source #
Instance details Defined in PlutusTx.Foldable Methods foldMap :: Monoid m => (a -> m) -> Maybe a -> m Source #
Traversable Maybe Source #
Instance details Defined in PlutusTx.Traversable Methods traverse :: Applicative f => (a -> f b) -> Maybe a -> f (Maybe b) Source #
FoldableWithIndex () Maybe
Instance details Defined in WithIndex Methods ifoldMap :: Monoid m => (() -> a -> m) -> Maybe a -> m ifoldMap' :: Monoid m => (() -> a -> m) -> Maybe a -> m ifoldr :: (() -> a -> b -> b) -> b -> Maybe a -> b ifoldl :: (() -> b -> a -> b) -> b -> Maybe a -> b ifoldr' :: (() -> a -> b -> b) -> b -> Maybe a -> b ifoldl' :: (() -> b -> a -> b) -> b -> Maybe a -> b
FunctorWithIndex () Maybe
Instance details Defined in WithIndex Methods imap :: (() -> a -> b) -> Maybe a -> Maybe b
TraversableWithIndex () Maybe
Instance details Defined in WithIndex Methods itraverse :: Applicative f => (() -> a -> f b) -> Maybe a -> f (Maybe b)
MonadBaseControl Maybe Maybe
Instance details Defined in Control.Monad.Trans.Control Associated Types type StM Maybe a Methods liftBaseWith :: (RunInBase Maybe Maybe -> Maybe a) -> Maybe a restoreM :: StM Maybe a -> Maybe a
MonadError () Maybe
Instance details Defined in Control.Monad.Error.Class Methods throwError :: () -> Maybe a catchError :: Maybe a -> (() -> Maybe a) -> Maybe a
(Selector s, GToJSON' enc arity (K1 i (Maybe a) :: Type -> Type), KeyValuePair enc pairs, Monoid pairs) => RecordToPairs enc pairs arity (S1 s (K1 i (Maybe a) :: Type -> Type))
Instance details Defined in Data.Aeson.Types.ToJSON Methods recordToPairs :: Options -> ToArgs enc arity a0 -> S1 s (K1 i (Maybe a)) a0 -> pairs
Lift a => Lift (Maybe a :: Type)
Instance details Defined in Language.Haskell.TH.Syntax Methods lift :: Maybe a -> Q Exp Source # liftTyped :: Maybe a -> Q (TExp (Maybe a)) Source #
PrettyDefaultBy config (Maybe a) => PrettyBy config (Maybe a)
Instance details Defined in Text.PrettyBy.Internal Methods prettyBy :: config -> Maybe a -> Doc ann prettyListBy :: config -> [Maybe a] -> Doc ann
PrettyBy config a => DefaultPrettyBy config (Maybe a)
Instance details Defined in Text.PrettyBy.Internal Methods defaultPrettyBy :: config -> Maybe a -> Doc ann defaultPrettyListBy :: config -> [Maybe a] -> Doc ann
(Typeable DefaultUni a, Lift DefaultUni a) => Lift DefaultUni (Maybe a) Source #
Instance details Defined in PlutusTx.Lift.Instances Methods lift :: Maybe a -> RTCompile DefaultUni fun (Term TyName Name DefaultUni fun ()) Source #
(Selector s, FromJSON a) => RecordFromJSON' arity (S1 s (K1 i (Maybe a) :: Type -> Type))
Instance details Defined in Data.Aeson.Types.FromJSON Methods recordParseJSON' :: (ConName :* (TypeName :* (Options :* FromArgs arity a0))) -> Object -> Parser (S1 s (K1 i (Maybe a)) a0)
Eq a => Eq (Maybe a)	Since: base-2.1
Instance details Defined in GHC.Maybe Methods (==) :: Maybe a -> Maybe a -> Bool Source # (/=) :: Maybe a -> Maybe a -> Bool Source #
Data a => Data (Maybe a)	Since: base-4.0.0.0
Instance details Defined in Data.Data Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Maybe a -> c (Maybe a) Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Maybe a) Source # toConstr :: Maybe a -> Constr Source # dataTypeOf :: Maybe a -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Maybe a)) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Maybe a)) Source # gmapT :: (forall b. Data b => b -> b) -> Maybe a -> Maybe a Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Maybe a -> r Source # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Maybe a -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Maybe a -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Maybe a -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a) Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a) Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Maybe a -> m (Maybe a) Source #
Ord a => Ord (Maybe a)	Since: base-2.1
Instance details Defined in GHC.Maybe Methods compare :: Maybe a -> Maybe a -> Ordering Source # (<) :: Maybe a -> Maybe a -> Bool Source # (<=) :: Maybe a -> Maybe a -> Bool Source # (>) :: Maybe a -> Maybe a -> Bool Source # (>=) :: Maybe a -> Maybe a -> Bool Source # max :: Maybe a -> Maybe a -> Maybe a Source # min :: Maybe a -> Maybe a -> Maybe a Source #
Read a => Read (Maybe a)	Since: base-2.1
Instance details Defined in GHC.Read Methods readsPrec :: Int -> ReadS (Maybe a) Source # readList :: ReadS [Maybe a] Source # readPrec :: ReadPrec (Maybe a) Source # readListPrec :: ReadPrec [Maybe a] Source #
Show a => Show (Maybe a)	Since: base-2.1
Instance details Defined in GHC.Show Methods showsPrec :: Int -> Maybe a -> ShowS Source # show :: Maybe a -> String Source # showList :: [Maybe a] -> ShowS Source #
Generic (Maybe a)	Since: base-4.6.0.0
Instance details Defined in GHC.Generics Associated Types type Rep (Maybe a) :: Type -> Type Source # Methods from :: Maybe a -> Rep (Maybe a) x Source # to :: Rep (Maybe a) x -> Maybe a Source #
Semigroup a => Semigroup (Maybe a)	Since: base-4.9.0.0
Instance details Defined in GHC.Base Methods (<>) :: Maybe a -> Maybe a -> Maybe a Source # sconcat :: NonEmpty (Maybe a) -> Maybe a Source # stimes :: Integral b => b -> Maybe a -> Maybe a Source #
Semigroup a => Monoid (Maybe a)	Lift a semigroup into `Maybe` forming a `Monoid` according to http://en.wikipedia.org/wiki/Monoid: "Any semigroup `S` may be turned into a monoid simply by adjoining an element `e` not in `S` and defining `ee = e` and `es = s = se` for all `s ∈ S`." Since 4.11.0: constraint on inner `a` value generalised from `Monoid` to `Semigroup`. Since: base-2.1*
Instance details Defined in GHC.Base Methods mempty :: Maybe a Source # mappend :: Maybe a -> Maybe a -> Maybe a Source # mconcat :: [Maybe a] -> Maybe a Source #
NFData a => NFData (Maybe a)
Instance details Defined in Control.DeepSeq Methods rnf :: Maybe a -> () Source #
At (Maybe a)
Instance details Defined in Control.Lens.At Methods at :: Index (Maybe a) -> Lens' (Maybe a) (Maybe (IxValue (Maybe a)))
Ixed (Maybe a)
Instance details Defined in Control.Lens.At Methods ix :: Index (Maybe a) -> Traversal' (Maybe a) (IxValue (Maybe a))
AsEmpty (Maybe a)
Instance details Defined in Control.Lens.Empty Methods _Empty :: Prism' (Maybe a) ()
Serialise a => Serialise (Maybe a)
Instance details Defined in Codec.Serialise.Class Methods encode :: Maybe a -> Encoding decode :: Decoder s (Maybe a) encodeList :: [Maybe a] -> Encoding decodeList :: Decoder s [Maybe a]
FromJSON a => FromJSON (Maybe a)
Instance details Defined in Data.Aeson.Types.FromJSON Methods parseJSON :: Value -> Parser (Maybe a) parseJSONList :: Value -> Parser [Maybe a]
ToJSON a => ToJSON (Maybe a)
Instance details Defined in Data.Aeson.Types.ToJSON Methods toJSON :: Maybe a -> Value toEncoding :: Maybe a -> Encoding toJSONList :: [Maybe a] -> Value toEncodingList :: [Maybe a] -> Encoding
Pretty a => Pretty (Maybe a)
Instance details Defined in Prettyprinter.Internal Methods pretty :: Maybe a -> Doc ann prettyList :: [Maybe a] -> Doc ann
Corecursive (Maybe a)
Instance details Defined in Data.Functor.Foldable Methods embed :: Base (Maybe a) (Maybe a) -> Maybe a ana :: (a0 -> Base (Maybe a) a0) -> a0 -> Maybe a apo :: (a0 -> Base (Maybe a) (Either (Maybe a) a0)) -> a0 -> Maybe a postpro :: Recursive (Maybe a) => (forall b. Base (Maybe a) b -> Base (Maybe a) b) -> (a0 -> Base (Maybe a) a0) -> a0 -> Maybe a gpostpro :: (Recursive (Maybe a), Monad m) => (forall b. m (Base (Maybe a) b) -> Base (Maybe a) (m b)) -> (forall c. Base (Maybe a) c -> Base (Maybe a) c) -> (a0 -> Base (Maybe a) (m a0)) -> a0 -> Maybe a
Recursive (Maybe a)
Instance details Defined in Data.Functor.Foldable Methods project :: Maybe a -> Base (Maybe a) (Maybe a) cata :: (Base (Maybe a) a0 -> a0) -> Maybe a -> a0 para :: (Base (Maybe a) (Maybe a, a0) -> a0) -> Maybe a -> a0 gpara :: (Corecursive (Maybe a), Comonad w) => (forall b. Base (Maybe a) (w b) -> w (Base (Maybe a) b)) -> (Base (Maybe a) (EnvT (Maybe a) w a0) -> a0) -> Maybe a -> a0 prepro :: Corecursive (Maybe a) => (forall b. Base (Maybe a) b -> Base (Maybe a) b) -> (Base (Maybe a) a0 -> a0) -> Maybe a -> a0 gprepro :: (Corecursive (Maybe a), Comonad w) => (forall b. Base (Maybe a) (w b) -> w (Base (Maybe a) b)) -> (forall c. Base (Maybe a) c -> Base (Maybe a) c) -> (Base (Maybe a) (w a0) -> a0) -> Maybe a -> a0
Hashable a => Hashable (Maybe a)
Instance details Defined in Data.Hashable.Class Methods hashWithSalt :: Int -> Maybe a -> Int hash :: Maybe a -> Int
SingKind a => SingKind (Maybe a)	Since: base-4.9.0.0
Instance details Defined in GHC.Generics Associated Types type DemoteRep (Maybe a) Methods fromSing :: forall (a0 :: Maybe a). Sing a0 -> DemoteRep (Maybe a)
MonoFoldable (Maybe a)
Instance details Defined in Data.MonoTraversable Methods ofoldMap :: Monoid m => (Element (Maybe a) -> m) -> Maybe a -> m ofoldr :: (Element (Maybe a) -> b -> b) -> b -> Maybe a -> b ofoldl' :: (a0 -> Element (Maybe a) -> a0) -> a0 -> Maybe a -> a0 otoList :: Maybe a -> [Element (Maybe a)] oall :: (Element (Maybe a) -> Bool) -> Maybe a -> Bool oany :: (Element (Maybe a) -> Bool) -> Maybe a -> Bool onull :: Maybe a -> Bool olength :: Maybe a -> Int olength64 :: Maybe a -> Int64 ocompareLength :: Integral i => Maybe a -> i -> Ordering otraverse_ :: Applicative f => (Element (Maybe a) -> f b) -> Maybe a -> f () ofor_ :: Applicative f => Maybe a -> (Element (Maybe a) -> f b) -> f () omapM_ :: Applicative m => (Element (Maybe a) -> m ()) -> Maybe a -> m () oforM_ :: Applicative m => Maybe a -> (Element (Maybe a) -> m ()) -> m () ofoldlM :: Monad m => (a0 -> Element (Maybe a) -> m a0) -> a0 -> Maybe a -> m a0 ofoldMap1Ex :: Semigroup m => (Element (Maybe a) -> m) -> Maybe a -> m ofoldr1Ex :: (Element (Maybe a) -> Element (Maybe a) -> Element (Maybe a)) -> Maybe a -> Element (Maybe a) ofoldl1Ex' :: (Element (Maybe a) -> Element (Maybe a) -> Element (Maybe a)) -> Maybe a -> Element (Maybe a) headEx :: Maybe a -> Element (Maybe a) lastEx :: Maybe a -> Element (Maybe a) unsafeHead :: Maybe a -> Element (Maybe a) unsafeLast :: Maybe a -> Element (Maybe a) maximumByEx :: (Element (Maybe a) -> Element (Maybe a) -> Ordering) -> Maybe a -> Element (Maybe a) minimumByEx :: (Element (Maybe a) -> Element (Maybe a) -> Ordering) -> Maybe a -> Element (Maybe a) oelem :: Element (Maybe a) -> Maybe a -> Bool onotElem :: Element (Maybe a) -> Maybe a -> Bool
MonoTraversable (Maybe a)
Instance details Defined in Data.MonoTraversable Methods otraverse :: Applicative f => (Element (Maybe a) -> f (Element (Maybe a))) -> Maybe a -> f (Maybe a) omapM :: Applicative m => (Element (Maybe a) -> m (Element (Maybe a))) -> Maybe a -> m (Maybe a)
MonoFunctor (Maybe a)
Instance details Defined in Data.MonoTraversable Methods omap :: (Element (Maybe a) -> Element (Maybe a)) -> Maybe a -> Maybe a
MonoPointed (Maybe a)
Instance details Defined in Data.MonoTraversable Methods opoint :: Element (Maybe a) -> Maybe a
Pretty a => Pretty (Maybe a)
Instance details Defined in Text.PrettyPrint.Annotated.WL Methods pretty :: Maybe a -> Doc b prettyList :: [Maybe a] -> Doc b
Graph g => Graph (Maybe g)
Instance details Defined in Algebra.Graph.Class Associated Types type Vertex (Maybe g) Methods empty :: Maybe g vertex :: Vertex (Maybe g) -> Maybe g overlay :: Maybe g -> Maybe g -> Maybe g connect :: Maybe g -> Maybe g -> Maybe g
Preorder g => Preorder (Maybe g)
Instance details Defined in Algebra.Graph.Class
Reflexive g => Reflexive (Maybe g)
Instance details Defined in Algebra.Graph.Class
Transitive g => Transitive (Maybe g)
Instance details Defined in Algebra.Graph.Class
Undirected g => Undirected (Maybe g)
Instance details Defined in Algebra.Graph.Class
Eq a => Eq (Maybe a) Source #
Instance details Defined in PlutusTx.Eq Methods (==) :: Maybe a -> Maybe a -> Bool Source #
Ord a => Ord (Maybe a) Source #
Instance details Defined in PlutusTx.Ord Methods compare :: Maybe a -> Maybe a -> Ordering Source # (<) :: Maybe a -> Maybe a -> Bool Source # (<=) :: Maybe a -> Maybe a -> Bool Source # (>) :: Maybe a -> Maybe a -> Bool Source # (>=) :: Maybe a -> Maybe a -> Bool Source # max :: Maybe a -> Maybe a -> Maybe a Source # min :: Maybe a -> Maybe a -> Maybe a Source #
Semigroup a => Semigroup (Maybe a) Source #
Instance details Defined in PlutusTx.Semigroup Methods (<>) :: Maybe a -> Maybe a -> Maybe a Source #
Semigroup a => Monoid (Maybe a) Source #
Instance details Defined in PlutusTx.Monoid Methods mempty :: Maybe a Source #
UnsafeFromData a => UnsafeFromData (Maybe a) Source #
Instance details Defined in PlutusTx.IsData.Instances Methods unsafeFromBuiltinData :: BuiltinData -> Maybe a Source #
FromData a => FromData (Maybe a) Source #
Instance details Defined in PlutusTx.IsData.Instances Methods fromBuiltinData :: BuiltinData -> Maybe (Maybe a) Source #
ToData a => ToData (Maybe a) Source #
Instance details Defined in PlutusTx.IsData.Instances Methods toBuiltinData :: Maybe a -> BuiltinData Source #
Generic1 Maybe	Since: base-4.6.0.0
Instance details Defined in GHC.Generics Associated Types type Rep1 Maybe :: k -> Type Source # Methods from1 :: forall (a :: k). Maybe a -> Rep1 Maybe a Source # to1 :: forall (a :: k). Rep1 Maybe a -> Maybe a Source #
SingI ('Nothing :: Maybe a)	Since: base-4.9.0.0
Instance details Defined in GHC.Generics Methods sing :: Sing 'Nothing
Each (Maybe a) (Maybe b) a b
Instance details Defined in Control.Lens.Each Methods each :: Traversal (Maybe a) (Maybe b) a b
Each (Maybe a) (Maybe b) a b
Instance details Defined in Lens.Micro.Internal Methods each :: Traversal (Maybe a) (Maybe b) a b
SingI a2 => SingI ('Just a2 :: Maybe a1)	Since: base-4.9.0.0
Instance details Defined in GHC.Generics Methods sing :: Sing ('Just a2)
Typeable DefaultUni Maybe Source #
Instance details Defined in PlutusTx.Lift.Instances Methods typeRep :: Proxy Maybe -> RTCompile DefaultUni fun (Type TyName DefaultUni ()) Source #
type Failure Maybe
Instance details Defined in Basement.Monad type Failure Maybe = ()
type StM Maybe a
Instance details Defined in Control.Monad.Trans.Control type StM Maybe a = a
type Rep (Maybe a)
Instance details Defined in GHC.Generics type Rep (Maybe a) = D1 ('MetaData "Maybe" "GHC.Maybe" "base" 'False) (C1 ('MetaCons "Nothing" 'PrefixI 'False) (U1 :: Type -> Type) :+: C1 ('MetaCons "Just" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 a)))
type Index (Maybe a)
Instance details Defined in Control.Lens.At type Index (Maybe a) = ()
type IxValue (Maybe a)
Instance details Defined in Control.Lens.At type IxValue (Maybe a) = a
type Base (Maybe a)
Instance details Defined in Data.Functor.Foldable type Base (Maybe a) = Const (Maybe a) :: Type -> Type
type Element (Maybe a)
Instance details Defined in Data.MonoTraversable type Element (Maybe a) = a
type DemoteRep (Maybe a)
Instance details Defined in GHC.Generics type DemoteRep (Maybe a) = Maybe (DemoteRep a)
data Sing (b :: Maybe a)
Instance details Defined in GHC.Generics data Sing (b :: Maybe a) where SNothing :: forall a. Sing ('Nothing :: Maybe a) SJust :: forall a (a1 :: a). Sing a1 -> Sing ('Just a1)
type Vertex (Maybe g)
Instance details Defined in Algebra.Graph.Class type Vertex (Maybe g) = Vertex g
type Rep1 Maybe
Instance details Defined in GHC.Generics type Rep1 Maybe = D1 ('MetaData "Maybe" "GHC.Maybe" "base" 'False) (C1 ('MetaCons "Nothing" 'PrefixI 'False) (U1 :: Type -> Type) :+: C1 ('MetaCons "Just" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) Par1))

isJust :: Maybe a -> Bool Source #

Check if a Maybe a is Just a

>>> isJust Nothing
False
>>> isJust (Just "plutus")
True

isNothing :: Maybe a -> Bool Source #

Check if a Maybe a is Nothing

>>> isNothing Nothing
True
>>> isNothing (Just "plutus")
False

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

Plutus Tx version of maybe.

>>> maybe "platypus" (\s -> s) (Just "plutus")
"plutus"
>>> maybe "platypus" (\s -> s) Nothing
"platypus"

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

Plutus Tx version of fromMaybe

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

Plutus Tx version of mapMaybe.

>>> mapMaybe (\i -> if i == 2 then Just '2' else Nothing) [1, 2, 3, 4]
"2"