Safe Haskell	Safe-Inferred
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

FromJSON1 Maybe
Instance details Defined in Data.Aeson.Types.FromJSON Methods liftParseJSON :: (Value -> Parser a) -> (Value -> Parser [a]) -> Value -> Parser (Maybe a) Source # liftParseJSONList :: (Value -> Parser a) -> (Value -> Parser [a]) -> Value -> Parser [Maybe a] Source #
ToJSON1 Maybe
Instance details Defined in Data.Aeson.Types.ToJSON Methods liftToJSON :: (a -> Value) -> ([a] -> Value) -> Maybe a -> Value Source # liftToJSONList :: (a -> Value) -> ([a] -> Value) -> [Maybe a] -> Value Source # liftToEncoding :: (a -> Encoding) -> ([a] -> Encoding) -> Maybe a -> Encoding Source # liftToEncodingList :: (a -> Encoding) -> ([a] -> Encoding) -> [Maybe a] -> Encoding Source #
MonadFail Maybe	Since: base-4.9.0.0
Instance details Defined in Control.Monad.Fail Methods fail :: String -> Maybe a Source #
MonadFix Maybe	Since: base-2.1
Instance details Defined in Control.Monad.Fix Methods mfix :: (a -> Maybe a) -> 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 #
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 #
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 #
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 #
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 #
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 #
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 #
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 #
MonadFailure Maybe
Instance details Defined in Basement.Monad Associated Types type Failure Maybe Source # Methods mFail :: Failure Maybe -> Maybe () Source #
NFData1 Maybe	Since: deepseq-1.4.3.0
Instance details Defined in Control.DeepSeq Methods liftRnf :: (a -> ()) -> Maybe a -> () Source #
Hashable1 Maybe
Instance details Defined in Data.Hashable.Class Methods liftHashWithSalt :: (Int -> a -> Int) -> Int -> Maybe a -> Int Source #
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 #
Functor Maybe Source #
Instance details Defined in PlutusTx.Functor Methods fmap :: (a -> b) -> Maybe a -> Maybe b Source #
Traversable Maybe Source #
Instance details Defined in PlutusTx.Traversable Methods traverse :: Applicative f => (a -> f b) -> Maybe a -> f (Maybe b) Source #
Generic1 Maybe
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 #
FoldableWithIndex () Maybe
Instance details Defined in WithIndex Methods ifoldMap :: Monoid m => (() -> a -> m) -> Maybe a -> m Source # ifoldMap' :: Monoid m => (() -> a -> m) -> Maybe a -> m Source # ifoldr :: (() -> a -> b -> b) -> b -> Maybe a -> b Source # ifoldl :: (() -> b -> a -> b) -> b -> Maybe a -> b Source # ifoldr' :: (() -> a -> b -> b) -> b -> Maybe a -> b Source # ifoldl' :: (() -> b -> a -> b) -> b -> Maybe a -> b Source #
FunctorWithIndex () Maybe
Instance details Defined in WithIndex Methods imap :: (() -> a -> b) -> Maybe a -> Maybe b Source #
TraversableWithIndex () Maybe
Instance details Defined in WithIndex Methods itraverse :: Applicative f => (() -> a -> f b) -> Maybe a -> f (Maybe b) Source #
MonadBaseControl Maybe Maybe
Instance details Defined in Control.Monad.Trans.Control Associated Types type StM Maybe a Source # Methods liftBaseWith :: (RunInBase Maybe Maybe -> Maybe a) -> Maybe a Source # restoreM :: StM Maybe a -> Maybe a Source #
MonadError () Maybe	Since: mtl-2.2.2
Instance details Defined in Control.Monad.Error.Class Methods throwError :: () -> Maybe a Source # catchError :: Maybe a -> (() -> Maybe a) -> Maybe a Source #
(Selector s, GToJSON' enc arity (K1 i (Maybe a) :: TYPE LiftedRep -> Type), KeyValuePair enc pairs, Monoid pairs) => RecordToPairs enc pairs arity (S1 s (K1 i (Maybe a) :: TYPE LiftedRep -> Type))
Instance details Defined in Data.Aeson.Types.ToJSON Methods recordToPairs :: Options -> ToArgs enc arity a0 -> S1 s (K1 i (Maybe a)) a0 -> pairs
(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 #
PrettyBy config a => DefaultPrettyBy config (Maybe a)
Instance details Defined in Text.PrettyBy.Internal Methods defaultPrettyBy :: config -> Maybe a -> Doc ann Source # defaultPrettyListBy :: config -> [Maybe a] -> Doc ann Source #
PrettyDefaultBy config (Maybe a) => PrettyBy config (Maybe a)	By default a `[Maybe a]` is converted to `[a]` first and only then pretty-printed. `>>>` `braces $ prettyBy () (Just True)`{True} `>>>` `braces $ prettyBy () (Nothing :: Maybe Bool)`{} `>>>` `prettyBy () [Just False, Nothing, Just True]`[False, True] `>>>` `prettyBy () [Nothing, Just 'a', Just 'b', Nothing, Just 'c']`abc
Instance details Defined in Text.PrettyBy.Internal Methods prettyBy :: config -> Maybe a -> Doc ann Source # prettyListBy :: config -> [Maybe a] -> Doc ann Source #
Lift a => Lift (Maybe a :: Type)
Instance details Defined in Language.Haskell.TH.Syntax Methods lift :: Quote m => Maybe a -> m Exp Source # liftTyped :: forall (m :: Type -> Type). Quote m => Maybe a -> Code m (Maybe a) 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)
FromJSON a => FromJSON (Maybe a)
Instance details Defined in Data.Aeson.Types.FromJSON Methods parseJSON :: Value -> Parser (Maybe a) Source # parseJSONList :: Value -> Parser [Maybe a] Source #
ToJSON a => ToJSON (Maybe a)
Instance details Defined in Data.Aeson.Types.ToJSON Methods toJSON :: Maybe a -> Value Source # toEncoding :: Maybe a -> Encoding Source # toJSONList :: [Maybe a] -> Value Source # toEncodingList :: [Maybe a] -> Encoding Source #
Graph g => Graph (Maybe g)
Instance details Defined in Algebra.Graph.Class Associated Types type Vertex (Maybe g) Source # Methods empty :: Maybe g Source # vertex :: Vertex (Maybe g) -> Maybe g Source # overlay :: Maybe g -> Maybe g -> Maybe g Source # connect :: Maybe g -> Maybe g -> Maybe g Source #
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
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 #
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 #
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 #
Generic (Maybe a)
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 #
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)
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 #
Default (Maybe a)
Instance details Defined in Data.Default.Class Methods def :: Maybe a Source #
NFData a => NFData (Maybe a)
Instance details Defined in Control.DeepSeq Methods rnf :: Maybe a -> () Source #
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 #
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 #
Hashable a => Hashable (Maybe a)
Instance details Defined in Data.Hashable.Class Methods hashWithSalt :: Int -> Maybe a -> Int Source # hash :: Maybe a -> Int Source #
At (Maybe a)
Instance details Defined in Control.Lens.At Methods at :: Index (Maybe a) -> Lens' (Maybe a) (Maybe (IxValue (Maybe a))) Source #
Ixed (Maybe a)
Instance details Defined in Control.Lens.At Methods ix :: Index (Maybe a) -> Traversal' (Maybe a) (IxValue (Maybe a)) Source #
AsEmpty (Maybe a)
Instance details Defined in Control.Lens.Empty Methods _Empty :: Prism' (Maybe a) () Source #
MonoFoldable (Maybe a)
Instance details Defined in Data.MonoTraversable Methods ofoldMap :: Monoid m => (Element (Maybe a) -> m) -> Maybe a -> m Source # ofoldr :: (Element (Maybe a) -> b -> b) -> b -> Maybe a -> b Source # ofoldl' :: (a0 -> Element (Maybe a) -> a0) -> a0 -> Maybe a -> a0 Source # otoList :: Maybe a -> [Element (Maybe a)] Source # oall :: (Element (Maybe a) -> Bool) -> Maybe a -> Bool Source # oany :: (Element (Maybe a) -> Bool) -> Maybe a -> Bool Source # onull :: Maybe a -> Bool Source # olength :: Maybe a -> Int Source # olength64 :: Maybe a -> Int64 Source # ocompareLength :: Integral i => Maybe a -> i -> Ordering Source # otraverse_ :: Applicative f => (Element (Maybe a) -> f b) -> Maybe a -> f () Source # ofor_ :: Applicative f => Maybe a -> (Element (Maybe a) -> f b) -> f () Source # omapM_ :: Applicative m => (Element (Maybe a) -> m ()) -> Maybe a -> m () Source # oforM_ :: Applicative m => Maybe a -> (Element (Maybe a) -> m ()) -> m () Source # ofoldlM :: Monad m => (a0 -> Element (Maybe a) -> m a0) -> a0 -> Maybe a -> m a0 Source # ofoldMap1Ex :: Semigroup m => (Element (Maybe a) -> m) -> Maybe a -> m Source # ofoldr1Ex :: (Element (Maybe a) -> Element (Maybe a) -> Element (Maybe a)) -> Maybe a -> Element (Maybe a) Source # ofoldl1Ex' :: (Element (Maybe a) -> Element (Maybe a) -> Element (Maybe a)) -> Maybe a -> Element (Maybe a) Source # headEx :: Maybe a -> Element (Maybe a) Source # lastEx :: Maybe a -> Element (Maybe a) Source # unsafeHead :: Maybe a -> Element (Maybe a) Source # unsafeLast :: Maybe a -> Element (Maybe a) Source # maximumByEx :: (Element (Maybe a) -> Element (Maybe a) -> Ordering) -> Maybe a -> Element (Maybe a) Source # minimumByEx :: (Element (Maybe a) -> Element (Maybe a) -> Ordering) -> Maybe a -> Element (Maybe a) Source # oelem :: Element (Maybe a) -> Maybe a -> Bool Source # onotElem :: Element (Maybe a) -> Maybe a -> Bool Source #
MonoFunctor (Maybe a)
Instance details Defined in Data.MonoTraversable Methods omap :: (Element (Maybe a) -> Element (Maybe a)) -> Maybe a -> Maybe a Source #
MonoPointed (Maybe a)
Instance details Defined in Data.MonoTraversable Methods opoint :: Element (Maybe a) -> Maybe a Source #
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) Source # omapM :: Applicative m => (Element (Maybe a) -> m (Element (Maybe a))) -> Maybe a -> m (Maybe a) Source #
Eq a => Eq (Maybe a) Source #
Instance details Defined in PlutusTx.Eq Methods (==) :: Maybe a -> Maybe a -> Bool 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 #
UnsafeFromData a => UnsafeFromData (Maybe a) Source #
Instance details Defined in PlutusTx.IsData.Instances Methods unsafeFromBuiltinData :: BuiltinData -> Maybe a Source #
Semigroup a => Monoid (Maybe a) Source #
Instance details Defined in PlutusTx.Monoid Methods mempty :: Maybe a 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 #
Show a => Show (Maybe a) Source #
Instance details Defined in PlutusTx.Show Methods showsPrec :: Integer -> Maybe a -> ShowS Source # show :: Maybe a -> BuiltinString Source #
Pretty a => Pretty (Maybe a)	Ignore `Nothing`s, print `Just` contents. `>>>` `pretty (Just True)`True `>>>` `braces (pretty (Nothing :: Maybe Bool))`{} `>>>` `pretty [Just 1, Nothing, Just 3, Nothing]`[1, 3]
Instance details Defined in Prettyprinter.Internal Methods pretty :: Maybe a -> Doc ann Source # prettyList :: [Maybe a] -> Doc ann Source #
Corecursive (Maybe a)
Instance details Defined in Data.Functor.Foldable Methods embed :: Base (Maybe a) (Maybe a) -> Maybe a Source # ana :: (a0 -> Base (Maybe a) a0) -> a0 -> Maybe a Source # apo :: (a0 -> Base (Maybe a) (Either (Maybe a) a0)) -> a0 -> Maybe a Source # postpro :: Recursive (Maybe a) => (forall b. Base (Maybe a) b -> Base (Maybe a) b) -> (a0 -> Base (Maybe a) a0) -> a0 -> Maybe a Source # 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 Source #
Recursive (Maybe a)
Instance details Defined in Data.Functor.Foldable Methods project :: Maybe a -> Base (Maybe a) (Maybe a) Source # cata :: (Base (Maybe a) a0 -> a0) -> Maybe a -> a0 Source # para :: (Base (Maybe a) (Maybe a, a0) -> a0) -> Maybe a -> a0 Source # 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 Source # prepro :: Corecursive (Maybe a) => (forall b. Base (Maybe a) b -> Base (Maybe a) b) -> (Base (Maybe a) a0 -> a0) -> Maybe a -> a0 Source # 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 Source #
Serialise a => Serialise (Maybe a)	Since: serialise-0.2.0.0
Instance details Defined in Codec.Serialise.Class Methods encode :: Maybe a -> Encoding Source # decode :: Decoder s (Maybe a) Source # encodeList :: [Maybe a] -> Encoding Source # decodeList :: Decoder s [Maybe a] Source #
Pretty a => Pretty (Maybe a)
Instance details Defined in Text.PrettyPrint.Annotated.WL Methods pretty :: Maybe a -> Doc b Source # prettyList :: [Maybe a] -> Doc b 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	`each` :: `Traversal` (`Maybe` a) (`Maybe` b) a b
Instance details Defined in Control.Lens.Each Methods each :: Traversal (Maybe a) (Maybe b) a b Source #
Each (Maybe a) (Maybe b) a b
Instance details Defined in Lens.Micro.Internal Methods each :: Traversal (Maybe a) (Maybe b) a b Source #
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 Rep1 Maybe	Since: base-4.6.0.0
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))
type StM Maybe a
Instance details Defined in Control.Monad.Trans.Control type StM Maybe a = a
type Vertex (Maybe g)
Instance details Defined in Algebra.Graph.Class type Vertex (Maybe g) = Vertex g
type DemoteRep (Maybe a)
Instance details Defined in GHC.Generics type DemoteRep (Maybe a) = Maybe (DemoteRep a)
type Rep (Maybe a)	Since: base-4.6.0.0
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)))
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 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 Element (Maybe a)
Instance details Defined in Data.MonoTraversable type Element (Maybe a) = a
type Base (Maybe a)	Example boring stub for non-recursive data types
Instance details Defined in Data.Functor.Foldable type Base (Maybe a) = Const (Maybe a) :: Type -> Type

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"