| Safe Haskell | Safe-Inferred |
|---|---|
| Language | Haskell98 |
Text.XML.HaXml.XmlContent.Parser
Description
The class XmlContent is a kind of replacement for Read and Show:
it provides conversions between a generic XML tree representation
and your own more specialised typeful Haskell data trees.
If you are starting with a set of Haskell datatypes, use DrIFT to derive instances of this class for you: http://repetae.net/john/computer/haskell/DrIFT If you are starting with an XML DTD, use HaXml's tool DtdToHaskell to generate both the Haskell types and the corresponding instances.
This unified class interface replaces two previous (somewhat similar) classes: Haskell2Xml and Xml2Haskell. There was no real reason to have separate classes depending on how you originally defined your datatypes. However, some instances for basic types like lists will depend on which direction you are using. See Text.XML.HaXml.XmlContent and Text.XML.HaXml.XmlContent.Haskell.
Synopsis
- data Document i = Document Prolog (SymTab EntityDef) (Element i) [Misc]
- data Element i = Elem QName [Attribute] [Content i]
- data ElemTag = ElemTag QName [Attribute]
- data Content i
- type Attribute = (QName, AttValue)
- data AttValue = AttValue [Either String Reference]
- data Prolog = Prolog (Maybe XMLDecl) [Misc] (Maybe DocTypeDecl) [Misc]
- data Reference
- class HTypeable a => XmlContent a where
- parseContents :: XMLParser a
- toContents :: a -> [Content ()]
- xToChar :: a -> Char
- xFromChar :: Char -> a
- class XmlAttributes a where
- class XmlAttrType a where
- fromAttrToTyp :: String -> Attribute -> Maybe a
- toAttrFrTyp :: String -> a -> Maybe Attribute
- class Functor f => Applicative (f :: Type -> Type) where
- class Applicative f => Alternative (f :: Type -> Type) where
- (<$) :: Functor f => a -> f b -> f a
- (<**>) :: Applicative f => f a -> f (a -> b) -> f b
- liftA :: Applicative f => (a -> b) -> f a -> f b
- liftA3 :: Applicative f => (a -> b -> c -> d) -> f a -> f b -> f c -> f d
- (<$>) :: Functor f => (a -> b) -> f a -> f b
- satisfy :: (t -> Bool) -> Parser t t
- eof :: Parser t ()
- optional :: Alternative f => f a -> f (Maybe a)
- many1 :: PolyParse p => p a -> p [a]
- sepBy :: PolyParse p => p a -> p sep -> p [a]
- sepBy1 :: PolyParse p => p a -> p sep -> p [a]
- apply :: PolyParse p => p (a -> b) -> p a -> p b
- asum :: (Foldable t, Alternative f) => t (f a) -> f a
- newtype Const a (b :: k) = Const {
- getConst :: a
- bracket :: PolyParse p => p bra -> p ket -> p a -> p a
- newtype ZipList a = ZipList {
- getZipList :: [a]
- newtype WrappedArrow (a :: Type -> Type -> Type) b c = WrapArrow {
- unwrapArrow :: a b c
- newtype WrappedMonad (m :: Type -> Type) a = WrapMonad {
- unwrapMonad :: m a
- newtype Parser t a = P ([t] -> Result [t] a)
- data Result z a
- reparse :: [t] -> Parser t ()
- class (Functor p, Monad p, MonadFail p, Applicative p, Alternative p, Commitment p) => PolyParse (p :: Type -> Type)
- class Commitment (p :: Type -> Type) where
- discard :: PolyParse p => p a -> p b -> p a
- failBad :: PolyParse p => String -> p a
- adjustErrBad :: PolyParse p => p a -> (String -> String) -> p a
- oneOf :: PolyParse p => [p a] -> p a
- indent :: Int -> String -> String
- exactly :: PolyParse p => Int -> p a -> p [a]
- upto :: PolyParse p => Int -> p a -> p [a]
- bracketSep :: PolyParse p => p bra -> p sep -> p ket -> p a -> p [a]
- manyFinally :: PolyParse p => p a -> p z -> p [a]
- manyFinally' :: (PolyParse p, Show a) => p a -> p z -> p [a]
- onFail :: Parser t a -> Parser t a -> Parser t a
- next :: Parser t t
- satisfyMsg :: Show t => (t -> Bool) -> String -> Parser t t
- runParser :: Parser t a -> [t] -> (Either String a, [t])
- type XMLParser a = Parser (Content Posn) a
- content :: String -> XMLParser (Content Posn)
- posnElement :: [String] -> XMLParser (Posn, Element Posn)
- element :: [String] -> XMLParser (Element Posn)
- interior :: Element Posn -> XMLParser a -> XMLParser a
- inElement :: String -> XMLParser a -> XMLParser a
- text :: XMLParser String
- attributes :: XmlAttributes a => Element Posn -> XMLParser a
- posnElementWith :: (String -> String -> Bool) -> [String] -> XMLParser (Posn, Element Posn)
- elementWith :: (String -> String -> Bool) -> [String] -> XMLParser (Element Posn)
- inElementWith :: (String -> String -> Bool) -> String -> XMLParser a -> XMLParser a
- choice :: XmlContent a => (a -> b) -> XMLParser b -> XMLParser b
- definite :: XmlContent a => XMLParser a -> String -> String -> XMLParser a
- mkElem :: XmlContent a => a -> [Content ()] -> Content ()
- mkElemC :: String -> [Content ()] -> Content ()
- mkAttr :: String -> String -> Attribute
- toText :: String -> [Content ()]
- toCData :: String -> [Content ()]
- maybeToAttr :: (String -> a -> Maybe Attribute) -> String -> Maybe a -> Maybe Attribute
- defaultToAttr :: (String -> a -> Maybe Attribute) -> String -> Defaultable a -> Maybe Attribute
- definiteA :: (String -> Attribute -> Maybe a) -> String -> String -> [Attribute] -> a
- defaultA :: (String -> Attribute -> Maybe a) -> a -> String -> [Attribute] -> Defaultable a
- possibleA :: (String -> Attribute -> Maybe a) -> String -> [Attribute] -> Maybe a
- fromAttrToStr :: String -> Attribute -> Maybe String
- toAttrFrStr :: String -> String -> Maybe Attribute
- data Defaultable a
- = Default a
- | NonDefault a
- str2attr :: String -> AttValue
- attr2str :: AttValue -> String
- attval :: Read a => Element i -> a
- catMaybes :: [Maybe a] -> [a]
- module Text.XML.HaXml.TypeMapping
- data List1 a = NonEmpty [a]
- data ANYContent
- = (XmlContent a, Show a) => ANYContent a
- | UnConverted [Content Posn]
Re-export the relevant set of generic XML document type definitions
The symbol table stored in a document holds all its general entity reference definitions.
Constructors
| CElem (Element i) i | |
| CString Bool CharData i | bool is whether whitespace is significant |
| CRef Reference i | |
| CMisc Misc i |
The enabling classes, that define parsing/unparsing between Haskell
class HTypeable a => XmlContent a where Source #
The XmlContent class promises that an XML Content element can be
converted to and from a Haskell value.
Minimal complete definition
Methods
parseContents :: XMLParser a Source #
Convert from XML to Haskell
toContents :: a -> [Content ()] Source #
Convert from Haskell to XML
Dummy functions (for most types): used only in the Char instance for coercing lists of Char into String.
Instances
class XmlAttributes a where Source #
The XmlAttributes class promises that a list of XML tag attributes
can be converted to and from a Haskell value.
class XmlAttrType a where Source #
The XmlAttrType class promises that an attribute taking an XML
enumerated type can be converted to and from a Haskell value.
Auxiliaries for writing parsers in the XmlContent class
class Functor f => Applicative (f :: Type -> Type) where Source #
A functor with application, providing operations to
A minimal complete definition must include implementations of pure
and of either <*> or liftA2. If it defines both, then they must behave
the same as their default definitions:
(<*>) =liftA2id
liftA2f x y = f<$>x<*>y
Further, any definition must satisfy the following:
- Identity
pureid<*>v = v- Composition
pure(.)<*>u<*>v<*>w = u<*>(v<*>w)- Homomorphism
puref<*>purex =pure(f x)- Interchange
u
<*>purey =pure($y)<*>u
The other methods have the following default definitions, which may be overridden with equivalent specialized implementations:
As a consequence of these laws, the Functor instance for f will satisfy
It may be useful to note that supposing
forall x y. p (q x y) = f x . g y
it follows from the above that
liftA2p (liftA2q u v) =liftA2f u .liftA2g v
If f is also a Monad, it should satisfy
(which implies that pure and <*> satisfy the applicative functor laws).
Methods
Lift a value into the Structure.
Examples
>>>pure 1 :: Maybe IntJust 1
>>>pure 'z' :: [Char]"z"
>>>pure (pure ":D") :: Maybe [String]Just [":D"]
(<*>) :: f (a -> b) -> f a -> f b infixl 4 Source #
Sequential application.
A few functors support an implementation of <*> that is more
efficient than the default one.
Example
Used in combination with (<$>)(<*>)
>>>data MyState = MyState {arg1 :: Foo, arg2 :: Bar, arg3 :: Baz}
>>>produceFoo :: Applicative f => f Foo>>>produceBar :: Applicative f => f Bar>>>produceBaz :: Applicative f => f Baz
>>>mkState :: Applicative f => f MyState>>>mkState = MyState <$> produceFoo <*> produceBar <*> produceBaz
liftA2 :: (a -> b -> c) -> f a -> f b -> f c Source #
Lift a binary function to actions.
Some functors support an implementation of liftA2 that is more
efficient than the default one. In particular, if fmap is an
expensive operation, it is likely better to use liftA2 than to
fmap over the structure and then use <*>.
This became a typeclass method in 4.10.0.0. Prior to that, it was
a function defined in terms of <*> and fmap.
Example
>>>liftA2 (,) (Just 3) (Just 5)Just (3,5)
>>>liftA2 (+) [1, 2, 3] [4, 5, 6][5,6,7,6,7,8,7,8,9]
(*>) :: f a -> f b -> f b infixl 4 Source #
Sequence actions, discarding the value of the first argument.
Examples
If used in conjunction with the Applicative instance for Maybe,
you can chain Maybe computations, with a possible "early return"
in case of Nothing.
>>>Just 2 *> Just 3Just 3
>>>Nothing *> Just 3Nothing
Of course a more interesting use case would be to have effectful computations instead of just returning pure values.
>>>import Data.Char>>>import GHC.Internal.Text.ParserCombinators.ReadP>>>let p = string "my name is " *> munch1 isAlpha <* eof>>>readP_to_S p "my name is Simon"[("Simon","")]
(<*) :: f a -> f b -> f a infixl 4 Source #
Sequence actions, discarding the value of the second argument.
Instances
| Applicative Complex | Since: base-4.9.0.0 |
| Applicative First | Since: base-4.9.0.0 |
| Applicative Last | Since: base-4.9.0.0 |
| Applicative Max | Since: base-4.9.0.0 |
| Applicative Min | Since: base-4.9.0.0 |
| Applicative Put | |
| Applicative Seq | Since: containers-0.5.4 |
| Applicative Tree | |
| Applicative NonEmpty | Since: base-4.9.0.0 |
Defined in GHC.Internal.Base | |
| Applicative ZipList | f <$> ZipList xs1 <*> ... <*> ZipList xsN
= ZipList (zipWithN f xs1 ... xsN)where (\a b c -> stimes c [a, b]) <$> ZipList "abcd" <*> ZipList "567" <*> ZipList [1..]
= ZipList (zipWith3 (\a b c -> stimes c [a, b]) "abcd" "567" [1..])
= ZipList {getZipList = ["a5","b6b6","c7c7c7"]}Since: base-2.1 |
Defined in GHC.Internal.Functor.ZipList | |
| Applicative Par1 | Since: base-4.9.0.0 |
| Applicative P | Since: base-4.5.0.0 |
| Applicative ReadP | Since: base-4.6.0.0 |
Defined in GHC.Internal.Text.ParserCombinators.ReadP | |
| Applicative IO | Since: base-2.1 |
| Applicative Parser | |
Defined in Text.ParserCombinators.HuttonMeijer | |
| Applicative Parser | |
Defined in Text.ParserCombinators.Poly.ByteString | |
| Applicative Parser | |
Defined in Text.ParserCombinators.Poly.ByteStringChar | |
| Applicative Parser | |
Defined in Text.ParserCombinators.Poly.Text | |
| Applicative Maybe | Since: base-2.1 |
| Applicative Solo | Since: base-4.15 |
| Applicative [] | Since: base-2.1 |
| Monad m => Applicative (WrappedMonad m) | Since: base-2.1 |
Defined in Control.Applicative Methods pure :: a -> WrappedMonad m a Source # (<*>) :: WrappedMonad m (a -> b) -> WrappedMonad m a -> WrappedMonad m b Source # liftA2 :: (a -> b -> c) -> WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m c Source # (*>) :: WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m b Source # (<*) :: WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m a Source # | |
| Applicative (SetM s) | |
| Applicative (Either e) | Since: base-3.0 |
Defined in GHC.Internal.Data.Either | |
| Applicative (U1 :: Type -> Type) | Since: base-4.9.0.0 |
| Applicative (Parser t) | |
Defined in Text.ParserCombinators.Poly.Lazy | |
| Applicative (Parser t) | |
Defined in Text.ParserCombinators.Poly.Lex | |
| Applicative (Parser t) | |
Defined in Text.ParserCombinators.Poly.Parser | |
| Applicative (Parser s) | |
Defined in Text.ParserCombinators.Poly.StateText | |
| Monoid a => Applicative ((,) a) | For tuples, the ("hello ", (+15)) <*> ("world!", 2002)
("hello world!",2017)Since: base-2.1 |
| Arrow a => Applicative (WrappedArrow a b) | Since: base-2.1 |
Defined in Control.Applicative Methods pure :: a0 -> WrappedArrow a b a0 Source # (<*>) :: WrappedArrow a b (a0 -> b0) -> WrappedArrow a b a0 -> WrappedArrow a b b0 Source # liftA2 :: (a0 -> b0 -> c) -> WrappedArrow a b a0 -> WrappedArrow a b b0 -> WrappedArrow a b c Source # (*>) :: WrappedArrow a b a0 -> WrappedArrow a b b0 -> WrappedArrow a b b0 Source # (<*) :: WrappedArrow a b a0 -> WrappedArrow a b b0 -> WrappedArrow a b a0 Source # | |
| (Applicative f, Monad f) => Applicative (WhenMissing f x) | Equivalent to Since: containers-0.5.9 |
Defined in Data.IntMap.Internal Methods pure :: a -> WhenMissing f x a Source # (<*>) :: WhenMissing f x (a -> b) -> WhenMissing f x a -> WhenMissing f x b Source # liftA2 :: (a -> b -> c) -> WhenMissing f x a -> WhenMissing f x b -> WhenMissing f x c Source # (*>) :: WhenMissing f x a -> WhenMissing f x b -> WhenMissing f x b Source # (<*) :: WhenMissing f x a -> WhenMissing f x b -> WhenMissing f x a Source # | |
| Monoid m => Applicative (Const m :: Type -> Type) | Since: base-2.0.1 |
Defined in GHC.Internal.Data.Functor.Const | |
| (Generic1 f, Applicative (Rep1 f)) => Applicative (Generically1 f) | Since: base-4.17.0.0 |
Defined in GHC.Internal.Generics Methods pure :: a -> Generically1 f a Source # (<*>) :: Generically1 f (a -> b) -> Generically1 f a -> Generically1 f b Source # liftA2 :: (a -> b -> c) -> Generically1 f a -> Generically1 f b -> Generically1 f c Source # (*>) :: Generically1 f a -> Generically1 f b -> Generically1 f b Source # (<*) :: Generically1 f a -> Generically1 f b -> Generically1 f a Source # | |
| Applicative f => Applicative (Rec1 f) | Since: base-4.9.0.0 |
| Applicative (Parser s t) | |
Defined in Text.ParserCombinators.Poly.StateLazy Methods pure :: a -> Parser s t a Source # (<*>) :: Parser s t (a -> b) -> Parser s t a -> Parser s t b Source # liftA2 :: (a -> b -> c) -> Parser s t a -> Parser s t b -> Parser s t c Source # (*>) :: Parser s t a -> Parser s t b -> Parser s t b Source # (<*) :: Parser s t a -> Parser s t b -> Parser s t a Source # | |
| Applicative (Parser s t) | |
Defined in Text.ParserCombinators.Poly.StateParser Methods pure :: a -> Parser s t a Source # (<*>) :: Parser s t (a -> b) -> Parser s t a -> Parser s t b Source # liftA2 :: (a -> b -> c) -> Parser s t a -> Parser s t b -> Parser s t c Source # (*>) :: Parser s t a -> Parser s t b -> Parser s t b Source # (<*) :: Parser s t a -> Parser s t b -> Parser s t a Source # | |
| (Monoid a, Monoid b) => Applicative ((,,) a b) | Since: base-4.14.0.0 |
Defined in GHC.Internal.Base | |
| (Applicative f, Applicative g) => Applicative (Product f g) | Since: base-4.9.0.0 |
Defined in Data.Functor.Product Methods pure :: a -> Product f g a Source # (<*>) :: Product f g (a -> b) -> Product f g a -> Product f g b Source # liftA2 :: (a -> b -> c) -> Product f g a -> Product f g b -> Product f g c Source # (*>) :: Product f g a -> Product f g b -> Product f g b Source # (<*) :: Product f g a -> Product f g b -> Product f g a Source # | |
| (Monad f, Applicative f) => Applicative (WhenMatched f x y) | Equivalent to Since: containers-0.5.9 |
Defined in Data.IntMap.Internal Methods pure :: a -> WhenMatched f x y a Source # (<*>) :: WhenMatched f x y (a -> b) -> WhenMatched f x y a -> WhenMatched f x y b Source # liftA2 :: (a -> b -> c) -> WhenMatched f x y a -> WhenMatched f x y b -> WhenMatched f x y c Source # (*>) :: WhenMatched f x y a -> WhenMatched f x y b -> WhenMatched f x y b Source # (<*) :: WhenMatched f x y a -> WhenMatched f x y b -> WhenMatched f x y a Source # | |
| (Applicative f, Monad f) => Applicative (WhenMissing f k x) | Equivalent to Since: containers-0.5.9 |
Defined in Data.Map.Internal Methods pure :: a -> WhenMissing f k x a Source # (<*>) :: WhenMissing f k x (a -> b) -> WhenMissing f k x a -> WhenMissing f k x b Source # liftA2 :: (a -> b -> c) -> WhenMissing f k x a -> WhenMissing f k x b -> WhenMissing f k x c Source # (*>) :: WhenMissing f k x a -> WhenMissing f k x b -> WhenMissing f k x b Source # (<*) :: WhenMissing f k x a -> WhenMissing f k x b -> WhenMissing f k x a Source # | |
| (Applicative f, Applicative g) => Applicative (f :*: g) | Since: base-4.9.0.0 |
Defined in GHC.Internal.Generics | |
| Monoid c => Applicative (K1 i c :: Type -> Type) | Since: base-4.12.0.0 |
| Applicative (Parser s t e) | |
Defined in Text.ParserCombinators.HuttonMeijerWallace Methods pure :: a -> Parser s t e a Source # (<*>) :: Parser s t e (a -> b) -> Parser s t e a -> Parser s t e b Source # liftA2 :: (a -> b -> c) -> Parser s t e a -> Parser s t e b -> Parser s t e c Source # (*>) :: Parser s t e a -> Parser s t e b -> Parser s t e b Source # (<*) :: Parser s t e a -> Parser s t e b -> Parser s t e a Source # | |
| (Monoid a, Monoid b, Monoid c) => Applicative ((,,,) a b c) | Since: base-4.14.0.0 |
Defined in GHC.Internal.Base Methods pure :: a0 -> (a, b, c, a0) Source # (<*>) :: (a, b, c, a0 -> b0) -> (a, b, c, a0) -> (a, b, c, b0) Source # liftA2 :: (a0 -> b0 -> c0) -> (a, b, c, a0) -> (a, b, c, b0) -> (a, b, c, c0) Source # (*>) :: (a, b, c, a0) -> (a, b, c, b0) -> (a, b, c, b0) Source # (<*) :: (a, b, c, a0) -> (a, b, c, b0) -> (a, b, c, a0) Source # | |
| Applicative ((->) r) | Since: base-2.1 |
| (Applicative f, Applicative g) => Applicative (Compose f g) | Since: base-4.9.0.0 |
Defined in Data.Functor.Compose Methods pure :: a -> Compose f g a Source # (<*>) :: Compose f g (a -> b) -> Compose f g a -> Compose f g b Source # liftA2 :: (a -> b -> c) -> Compose f g a -> Compose f g b -> Compose f g c Source # (*>) :: Compose f g a -> Compose f g b -> Compose f g b Source # (<*) :: Compose f g a -> Compose f g b -> Compose f g a Source # | |
| (Monad f, Applicative f) => Applicative (WhenMatched f k x y) | Equivalent to Since: containers-0.5.9 |
Defined in Data.Map.Internal Methods pure :: a -> WhenMatched f k x y a Source # (<*>) :: WhenMatched f k x y (a -> b) -> WhenMatched f k x y a -> WhenMatched f k x y b Source # liftA2 :: (a -> b -> c) -> WhenMatched f k x y a -> WhenMatched f k x y b -> WhenMatched f k x y c Source # (*>) :: WhenMatched f k x y a -> WhenMatched f k x y b -> WhenMatched f k x y b Source # (<*) :: WhenMatched f k x y a -> WhenMatched f k x y b -> WhenMatched f k x y a Source # | |
| (Applicative f, Applicative g) => Applicative (f :.: g) | Since: base-4.9.0.0 |
Defined in GHC.Internal.Generics | |
| Applicative f => Applicative (M1 i c f) | Since: base-4.9.0.0 |
Defined in GHC.Internal.Generics | |
class Applicative f => Alternative (f :: Type -> Type) where Source #
A monoid on applicative functors.
If defined, some and many should be the least solutions
of the equations:
Examples
>>>Nothing <|> Just 42Just 42
>>>[1, 2] <|> [3, 4][1,2,3,4]
>>>empty <|> print (2^15)32768
Methods
The identity of <|>
empty <|> a == a a <|> empty == a
(<|>) :: f a -> f a -> f a infixl 3 Source #
An associative binary operation
One or more.
Examples
>>>some (putStr "la")lalalalalalalalala... * goes on forever *
>>>some Nothingnothing
>>>take 5 <$> some (Just 1)* hangs forever *
Note that this function can be used with Parsers based on
Applicatives. In that case some parser will attempt to
parse parser one or more times until it fails.
Zero or more.
Examples
>>>many (putStr "la")lalalalalalalalala... * goes on forever *
>>>many NothingJust []
>>>take 5 <$> many (Just 1)* hangs forever *
Note that this function can be used with Parsers based on
Applicatives. In that case many parser will attempt to
parse parser zero or more times until it fails.
Instances
| Alternative Seq | Since: containers-0.5.4 |
| Alternative ZipList | Since: base-4.11.0.0 |
| Alternative P | Since: base-4.5.0.0 |
| Alternative ReadP | Since: base-4.6.0.0 |
| Alternative IO | Takes the first non-throwing Since: base-4.9.0.0 |
| Alternative Parser | |
| Alternative Parser | |
| Alternative Parser | |
| Alternative Parser | |
| Alternative Maybe | Picks the leftmost Since: base-2.1 |
| Alternative [] | Combines lists by concatenation, starting from the empty list. Since: base-2.1 |
| MonadPlus m => Alternative (WrappedMonad m) | Since: base-2.1 |
Defined in Control.Applicative Methods empty :: WrappedMonad m a Source # (<|>) :: WrappedMonad m a -> WrappedMonad m a -> WrappedMonad m a Source # some :: WrappedMonad m a -> WrappedMonad m [a] Source # many :: WrappedMonad m a -> WrappedMonad m [a] Source # | |
| Alternative (U1 :: Type -> Type) | Since: base-4.9.0.0 |
| Alternative (Parser t) | |
| Alternative (Parser t) | |
| Alternative (Parser t) | |
| Alternative (Parser s) | |
| (ArrowZero a, ArrowPlus a) => Alternative (WrappedArrow a b) | Since: base-2.1 |
Defined in Control.Applicative Methods empty :: WrappedArrow a b a0 Source # (<|>) :: WrappedArrow a b a0 -> WrappedArrow a b a0 -> WrappedArrow a b a0 Source # some :: WrappedArrow a b a0 -> WrappedArrow a b [a0] Source # many :: WrappedArrow a b a0 -> WrappedArrow a b [a0] Source # | |
| (Generic1 f, Alternative (Rep1 f)) => Alternative (Generically1 f) | Since: base-4.17.0.0 |
Defined in GHC.Internal.Generics Methods empty :: Generically1 f a Source # (<|>) :: Generically1 f a -> Generically1 f a -> Generically1 f a Source # some :: Generically1 f a -> Generically1 f [a] Source # many :: Generically1 f a -> Generically1 f [a] Source # | |
| Alternative f => Alternative (Rec1 f) | Since: base-4.9.0.0 |
| Alternative (Parser s t) | |
| Alternative (Parser s t) | |
| (Alternative f, Alternative g) => Alternative (Product f g) | Since: base-4.9.0.0 |
| (Alternative f, Alternative g) => Alternative (f :*: g) | Since: base-4.9.0.0 |
| Alternative (Parser s t e) | |
| (Alternative f, Applicative g) => Alternative (Compose f g) | Since: base-4.9.0.0 |
| (Alternative f, Applicative g) => Alternative (f :.: g) | Since: base-4.9.0.0 |
| Alternative f => Alternative (M1 i c f) | Since: base-4.9.0.0 |
(<**>) :: Applicative f => f a -> f (a -> b) -> f b infixl 4 Source #
A variant of <*> with the types of the arguments reversed. It differs from
flip (<*>)
Examples
>>>(<**>) (print 1) (id <$ print 2)1 2
>>>flip (<*>) (print 1) (id <$ print 2)2 1
>>>ZipList [4, 5, 6] <**> ZipList [(+1), (*2), (/3)]ZipList {getZipList = [5.0,10.0,2.0]}
liftA :: Applicative f => (a -> b) -> f a -> f b Source #
Lift a function to actions.
Equivalent to Functor's fmap but implemented using only Applicative's methods:
liftA f a = pure f <*> a
As such this function may be used to implement a Functor instance from an Applicative one.
Examples
Using the Applicative instance for Lists:
>>>liftA (+1) [1, 2][2,3]
Or the Applicative instance for Maybe
>>>liftA (+1) (Just 3)Just 4
liftA3 :: Applicative f => (a -> b -> c -> d) -> f a -> f b -> f c -> f d Source #
Lift a ternary function to actions.
(<$>) :: Functor f => (a -> b) -> f a -> f b infixl 4 Source #
An infix synonym for fmap.
The name of this operator is an allusion to $.
Note the similarities between their types:
($) :: (a -> b) -> a -> b (<$>) :: Functor f => (a -> b) -> f a -> f b
Whereas $ is function application, <$> is function
application lifted over a Functor.
Examples
Convert from a Maybe IntMaybe
Stringshow:
>>>show <$> NothingNothing
>>>show <$> Just 3Just "3"
Convert from an Either Int IntEither IntString using show:
>>>show <$> Left 17Left 17
>>>show <$> Right 17Right "17"
Double each element of a list:
>>>(*2) <$> [1,2,3][2,4,6]
Apply even to the second element of a pair:
>>>even <$> (2,2)(2,True)
optional :: Alternative f => f a -> f (Maybe a) Source #
One or none.
It is useful for modelling any computation that is allowed to fail.
Examples
Using the Alternative instance of Control.Monad.Except, the following functions:
>>>import Control.Monad.Except
>>>canFail = throwError "it failed" :: Except String Int>>>final = return 42 :: Except String Int
Can be combined by allowing the first function to fail:
>>>runExcept $ canFail *> finalLeft "it failed"
>>>runExcept $ optional canFail *> finalRight 42
asum :: (Foldable t, Alternative f) => t (f a) -> f a Source #
The sum of a collection of actions using (<|>), generalizing concat.
asum is just like msum, but generalised to Alternative.
Examples
Basic usage:
>>>asum [Just "Hello", Nothing, Just "World"]Just "Hello"
newtype Const a (b :: k) Source #
The Const functor.
Examples
>>>fmap (++ "World") (Const "Hello")Const "Hello"
Because we ignore the second type parameter to Const,
the Applicative instance, which has
(<*>) :: Monoid m => Const m (a -> b) -> Const m a -> Const m bMonoid m => m -> m -> m, which is (<>)
>>>Const [1, 2, 3] <*> Const [4, 5, 6]Const [1,2,3,4,5,6]
Instances
Lists, but with an Applicative functor based on zipping.
Examples
In contrast to the Applicative for List:
>>>(+) <$> [1, 2, 3] <*> [4, 5, 6][5,6,7,6,7,8,7,8,9]
The Applicative instance of ZipList applies the operation
by pairing up the elements, analogous to zipWithN
>>>(+) <$> ZipList [1, 2, 3] <*> ZipList [4, 5, 6]ZipList {getZipList = [5,7,9]}
>>>(,,,) <$> ZipList [1, 2] <*> ZipList [3, 4] <*> ZipList [5, 6] <*> ZipList [7, 8]ZipList {getZipList = [(1,3,5,7),(2,4,6,8)]}
>>>ZipList [(+1), (^2), (/ 2)] <*> ZipList [5, 5, 5]ZipList {getZipList = [6.0,25.0,2.5]}
Constructors
| ZipList | |
Fields
| |
Instances
| Alternative ZipList | Since: base-4.11.0.0 | ||||
| Applicative ZipList | f <$> ZipList xs1 <*> ... <*> ZipList xsN
= ZipList (zipWithN f xs1 ... xsN)where (\a b c -> stimes c [a, b]) <$> ZipList "abcd" <*> ZipList "567" <*> ZipList [1..]
= ZipList (zipWith3 (\a b c -> stimes c [a, b]) "abcd" "567" [1..])
= ZipList {getZipList = ["a5","b6b6","c7c7c7"]}Since: base-2.1 | ||||
Defined in GHC.Internal.Functor.ZipList | |||||
| Functor ZipList | Since: base-2.1 | ||||
| Foldable ZipList | Since: base-4.9.0.0 | ||||
Defined in GHC.Internal.Functor.ZipList Methods fold :: Monoid m => ZipList m -> m Source # foldMap :: Monoid m => (a -> m) -> ZipList a -> m Source # foldMap' :: Monoid m => (a -> m) -> ZipList a -> m Source # foldr :: (a -> b -> b) -> b -> ZipList a -> b Source # foldr' :: (a -> b -> b) -> b -> ZipList a -> b Source # foldl :: (b -> a -> b) -> b -> ZipList a -> b Source # foldl' :: (b -> a -> b) -> b -> ZipList a -> b Source # foldr1 :: (a -> a -> a) -> ZipList a -> a Source # foldl1 :: (a -> a -> a) -> ZipList a -> a Source # toList :: ZipList a -> [a] Source # null :: ZipList a -> Bool Source # length :: ZipList a -> Int Source # elem :: Eq a => a -> ZipList a -> Bool Source # maximum :: Ord a => ZipList a -> a Source # minimum :: Ord a => ZipList a -> a Source # | |||||
| Traversable ZipList | Since: base-4.9.0.0 | ||||
Defined in GHC.Internal.Functor.ZipList | |||||
| Generic1 ZipList | |||||
Defined in GHC.Internal.Functor.ZipList Associated Types
| |||||
| Data a => Data (ZipList a) | Since: base-4.14.0.0 | ||||
Defined in GHC.Internal.Functor.ZipList Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> ZipList a -> c (ZipList a) Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (ZipList a) Source # toConstr :: ZipList a -> Constr Source # dataTypeOf :: ZipList a -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (ZipList a)) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (ZipList a)) Source # gmapT :: (forall b. Data b => b -> b) -> ZipList a -> ZipList a Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> ZipList a -> r Source # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> ZipList a -> r Source # gmapQ :: (forall d. Data d => d -> u) -> ZipList a -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> ZipList a -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> ZipList a -> m (ZipList a) Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> ZipList a -> m (ZipList a) Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> ZipList a -> m (ZipList a) Source # | |||||
| Generic (ZipList a) | |||||
Defined in GHC.Internal.Functor.ZipList Associated Types
| |||||
| IsList (ZipList a) | Since: base-4.15.0.0 | ||||
| Read a => Read (ZipList a) | Since: base-4.7.0.0 | ||||
| Show a => Show (ZipList a) | Since: base-4.7.0.0 | ||||
| Eq a => Eq (ZipList a) | Since: base-4.7.0.0 | ||||
| Ord a => Ord (ZipList a) | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Functor.ZipList | |||||
| type Rep1 ZipList | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Functor.ZipList | |||||
| type Rep (ZipList a) | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Functor.ZipList | |||||
| type Item (ZipList a) | |||||
Defined in GHC.Internal.IsList | |||||
newtype WrappedArrow (a :: Type -> Type -> Type) b c Source #
Constructors
| WrapArrow | |
Fields
| |
Instances
| Generic1 (WrappedArrow a b :: Type -> Type) | |||||
Defined in Control.Applicative Associated Types
Methods from1 :: WrappedArrow a b a0 -> Rep1 (WrappedArrow a b) a0 Source # to1 :: Rep1 (WrappedArrow a b) a0 -> WrappedArrow a b a0 Source # | |||||
| (ArrowZero a, ArrowPlus a) => Alternative (WrappedArrow a b) | Since: base-2.1 | ||||
Defined in Control.Applicative Methods empty :: WrappedArrow a b a0 Source # (<|>) :: WrappedArrow a b a0 -> WrappedArrow a b a0 -> WrappedArrow a b a0 Source # some :: WrappedArrow a b a0 -> WrappedArrow a b [a0] Source # many :: WrappedArrow a b a0 -> WrappedArrow a b [a0] Source # | |||||
| Arrow a => Applicative (WrappedArrow a b) | Since: base-2.1 | ||||
Defined in Control.Applicative Methods pure :: a0 -> WrappedArrow a b a0 Source # (<*>) :: WrappedArrow a b (a0 -> b0) -> WrappedArrow a b a0 -> WrappedArrow a b b0 Source # liftA2 :: (a0 -> b0 -> c) -> WrappedArrow a b a0 -> WrappedArrow a b b0 -> WrappedArrow a b c Source # (*>) :: WrappedArrow a b a0 -> WrappedArrow a b b0 -> WrappedArrow a b b0 Source # (<*) :: WrappedArrow a b a0 -> WrappedArrow a b b0 -> WrappedArrow a b a0 Source # | |||||
| Arrow a => Functor (WrappedArrow a b) | Since: base-2.1 | ||||
Defined in Control.Applicative Methods fmap :: (a0 -> b0) -> WrappedArrow a b a0 -> WrappedArrow a b b0 Source # (<$) :: a0 -> WrappedArrow a b b0 -> WrappedArrow a b a0 Source # | |||||
| (Typeable a, Typeable b, Typeable c, Data (a b c)) => Data (WrappedArrow a b c) | Since: base-4.14.0.0 | ||||
Defined in Control.Applicative Methods gfoldl :: (forall d b0. Data d => c0 (d -> b0) -> d -> c0 b0) -> (forall g. g -> c0 g) -> WrappedArrow a b c -> c0 (WrappedArrow a b c) Source # gunfold :: (forall b0 r. Data b0 => c0 (b0 -> r) -> c0 r) -> (forall r. r -> c0 r) -> Constr -> c0 (WrappedArrow a b c) Source # toConstr :: WrappedArrow a b c -> Constr Source # dataTypeOf :: WrappedArrow a b c -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c0 (t d)) -> Maybe (c0 (WrappedArrow a b c)) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c0 (t d e)) -> Maybe (c0 (WrappedArrow a b c)) Source # gmapT :: (forall b0. Data b0 => b0 -> b0) -> WrappedArrow a b c -> WrappedArrow a b c Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> WrappedArrow a b c -> r Source # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> WrappedArrow a b c -> r Source # gmapQ :: (forall d. Data d => d -> u) -> WrappedArrow a b c -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> WrappedArrow a b c -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> WrappedArrow a b c -> m (WrappedArrow a b c) Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> WrappedArrow a b c -> m (WrappedArrow a b c) Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> WrappedArrow a b c -> m (WrappedArrow a b c) Source # | |||||
| Generic (WrappedArrow a b c) | |||||
Defined in Control.Applicative Associated Types
Methods from :: WrappedArrow a b c -> Rep (WrappedArrow a b c) x Source # to :: Rep (WrappedArrow a b c) x -> WrappedArrow a b c Source # | |||||
| type Rep1 (WrappedArrow a b :: Type -> Type) | Since: base-4.7.0.0 | ||||
Defined in Control.Applicative type Rep1 (WrappedArrow a b :: Type -> Type) = D1 ('MetaData "WrappedArrow" "Control.Applicative" "base" 'True) (C1 ('MetaCons "WrapArrow" 'PrefixI 'True) (S1 ('MetaSel ('Just "unwrapArrow") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec1 (a b)))) | |||||
| type Rep (WrappedArrow a b c) | Since: base-4.7.0.0 | ||||
Defined in Control.Applicative type Rep (WrappedArrow a b c) = D1 ('MetaData "WrappedArrow" "Control.Applicative" "base" 'True) (C1 ('MetaCons "WrapArrow" 'PrefixI 'True) (S1 ('MetaSel ('Just "unwrapArrow") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (a b c)))) | |||||
newtype WrappedMonad (m :: Type -> Type) a Source #
Constructors
| WrapMonad | |
Fields
| |
Instances
| Generic1 (WrappedMonad m :: Type -> Type) | |||||
Defined in Control.Applicative Associated Types
Methods from1 :: WrappedMonad m a -> Rep1 (WrappedMonad m) a Source # to1 :: Rep1 (WrappedMonad m) a -> WrappedMonad m a Source # | |||||
| MonadPlus m => Alternative (WrappedMonad m) | Since: base-2.1 | ||||
Defined in Control.Applicative Methods empty :: WrappedMonad m a Source # (<|>) :: WrappedMonad m a -> WrappedMonad m a -> WrappedMonad m a Source # some :: WrappedMonad m a -> WrappedMonad m [a] Source # many :: WrappedMonad m a -> WrappedMonad m [a] Source # | |||||
| Monad m => Applicative (WrappedMonad m) | Since: base-2.1 | ||||
Defined in Control.Applicative Methods pure :: a -> WrappedMonad m a Source # (<*>) :: WrappedMonad m (a -> b) -> WrappedMonad m a -> WrappedMonad m b Source # liftA2 :: (a -> b -> c) -> WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m c Source # (*>) :: WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m b Source # (<*) :: WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m a Source # | |||||
| Monad m => Functor (WrappedMonad m) | Since: base-2.1 | ||||
Defined in Control.Applicative Methods fmap :: (a -> b) -> WrappedMonad m a -> WrappedMonad m b Source # (<$) :: a -> WrappedMonad m b -> WrappedMonad m a Source # | |||||
| Monad m => Monad (WrappedMonad m) | Since: base-4.7.0.0 | ||||
Defined in Control.Applicative Methods (>>=) :: WrappedMonad m a -> (a -> WrappedMonad m b) -> WrappedMonad m b Source # (>>) :: WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m b Source # return :: a -> WrappedMonad m a Source # | |||||
| (Typeable m, Typeable a, Data (m a)) => Data (WrappedMonad m a) | Since: base-4.14.0.0 | ||||
Defined in Control.Applicative Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> WrappedMonad m a -> c (WrappedMonad m a) Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (WrappedMonad m a) Source # toConstr :: WrappedMonad m a -> Constr Source # dataTypeOf :: WrappedMonad m a -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (WrappedMonad m a)) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (WrappedMonad m a)) Source # gmapT :: (forall b. Data b => b -> b) -> WrappedMonad m a -> WrappedMonad m a Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> WrappedMonad m a -> r Source # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> WrappedMonad m a -> r Source # gmapQ :: (forall d. Data d => d -> u) -> WrappedMonad m a -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> WrappedMonad m a -> u Source # gmapM :: Monad m0 => (forall d. Data d => d -> m0 d) -> WrappedMonad m a -> m0 (WrappedMonad m a) Source # gmapMp :: MonadPlus m0 => (forall d. Data d => d -> m0 d) -> WrappedMonad m a -> m0 (WrappedMonad m a) Source # gmapMo :: MonadPlus m0 => (forall d. Data d => d -> m0 d) -> WrappedMonad m a -> m0 (WrappedMonad m a) Source # | |||||
| Generic (WrappedMonad m a) | |||||
Defined in Control.Applicative Associated Types
Methods from :: WrappedMonad m a -> Rep (WrappedMonad m a) x Source # to :: Rep (WrappedMonad m a) x -> WrappedMonad m a Source # | |||||
| type Rep1 (WrappedMonad m :: Type -> Type) | Since: base-4.7.0.0 | ||||
Defined in Control.Applicative type Rep1 (WrappedMonad m :: Type -> Type) = D1 ('MetaData "WrappedMonad" "Control.Applicative" "base" 'True) (C1 ('MetaCons "WrapMonad" 'PrefixI 'True) (S1 ('MetaSel ('Just "unwrapMonad") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec1 m))) | |||||
| type Rep (WrappedMonad m a) | Since: base-4.7.0.0 | ||||
Defined in Control.Applicative type Rep (WrappedMonad m a) = D1 ('MetaData "WrappedMonad" "Control.Applicative" "base" 'True) (C1 ('MetaCons "WrapMonad" 'PrefixI 'True) (S1 ('MetaSel ('Just "unwrapMonad") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (m a)))) | |||||
Instances
| Alternative (Parser t) | |
| Applicative (Parser t) | |
Defined in Text.ParserCombinators.Poly.Parser | |
| Functor (Parser t) | |
| Monad (Parser t) | |
| MonadFail (Parser t) | |
| Commitment (Parser t) | |
| PolyParse (Parser t) | |
Defined in Text.ParserCombinators.Poly.Parser | |
class (Functor p, Monad p, MonadFail p, Applicative p, Alternative p, Commitment p) => PolyParse (p :: Type -> Type) #
Instances
| PolyParse Parser | |
Defined in Text.ParserCombinators.Poly.ByteString | |
| PolyParse Parser | |
Defined in Text.ParserCombinators.Poly.ByteStringChar | |
| PolyParse Parser | |
Defined in Text.ParserCombinators.Poly.Text | |
| PolyParse (Parser t) | |
Defined in Text.ParserCombinators.Poly.Lazy | |
| PolyParse (Parser t) | |
Defined in Text.ParserCombinators.Poly.Lex | |
| PolyParse (Parser t) | |
Defined in Text.ParserCombinators.Poly.Parser | |
| PolyParse (Parser s) | |
Defined in Text.ParserCombinators.Poly.StateText | |
| PolyParse (Parser s t) | |
Defined in Text.ParserCombinators.Poly.StateLazy | |
| PolyParse (Parser s t) | |
Defined in Text.ParserCombinators.Poly.StateParser | |
class Commitment (p :: Type -> Type) where #
Instances
| Commitment Parser | |
| Commitment Parser | |
| Commitment Parser | |
| Commitment (Parser t) | |
| Commitment (Parser t) | |
| Commitment (Parser t) | |
| Commitment (Parser s) | |
| Commitment (Parser s t) | |
| Commitment (Parser s t) | |
adjustErrBad :: PolyParse p => p a -> (String -> String) -> p a #
bracketSep :: PolyParse p => p bra -> p sep -> p ket -> p a -> p [a] #
manyFinally :: PolyParse p => p a -> p z -> p [a] #
manyFinally' :: (PolyParse p, Show a) => p a -> p z -> p [a] #
type XMLParser a = Parser (Content Posn) a Source #
We need a parsing monad for reading generic XML Content into specific datatypes. This is a specialisation of the Text.ParserCombinators.Poly ones, where the input token type is fixed as XML Content.
content :: String -> XMLParser (Content Posn) Source #
The most primitive combinator for XMLParser - get one content item.
posnElement :: [String] -> XMLParser (Posn, Element Posn) Source #
A specialisation of posnElementWith (==).
element :: [String] -> XMLParser (Element Posn) Source #
Get the next content element, checking that it has one of the required tags. (Skips over comments and whitespace, rejects text and refs.)
interior :: Element Posn -> XMLParser a -> XMLParser a Source #
Run an XMLParser on the contents of the given element (i.e. not on the current monadic content sequence), checking that the contents are exhausted, before returning the calculated value within the current parser context.
attributes :: XmlAttributes a => Element Posn -> XMLParser a Source #
Do some parsing of the attributes of the given element
posnElementWith :: (String -> String -> Bool) -> [String] -> XMLParser (Posn, Element Posn) Source #
Get the next content element, checking that it has one of the required tags, using the given matching function. (Skips over comments and whitespace, rejects text and refs. Also returns position of element.)
elementWith :: (String -> String -> Bool) -> [String] -> XMLParser (Element Posn) Source #
Like element, only permits a more flexible match against the tagname.
inElementWith :: (String -> String -> Bool) -> String -> XMLParser a -> XMLParser a Source #
A combination of elementWith + interior.
choice :: XmlContent a => (a -> b) -> XMLParser b -> XMLParser b Source #
'choice f p' means if parseContents succeeds, apply f to the result, otherwise use the continuation parser.
definite :: XmlContent a => XMLParser a -> String -> String -> XMLParser a Source #
not sure this is needed now. 'definite p' previously ensured that an element was definitely present. Now I think the monad might take care of that for us.
Auxiliaries for generating in the XmlContent class
mkElem :: XmlContent a => a -> [Content ()] -> Content () Source #
Generate an element with no attributes, named for its HType.
mkElemC :: String -> [Content ()] -> Content () Source #
Generate an element with no attributes, named directly.
toCData :: String -> [Content ()] Source #
Turn a string into an XML CDATA section.
(i.e. special characters like & are preserved without interpretation.)
Auxiliaries for the attribute-related classes
defaultToAttr :: (String -> a -> Maybe Attribute) -> String -> Defaultable a -> Maybe Attribute Source #
defaultA :: (String -> Attribute -> Maybe a) -> a -> String -> [Attribute] -> Defaultable a Source #
data Defaultable a Source #
If an attribute is defaultable, then it either takes the default value (which is omitted from the output), or a non-default value (which obviously must be printed).
Constructors
| Default a | |
| NonDefault a |
Instances
| Show a => Show (Defaultable a) Source # | |
Defined in Text.XML.HaXml.XmlContent.Parser | |
| Eq a => Eq (Defaultable a) Source # | |
Defined in Text.XML.HaXml.XmlContent.Parser Methods (==) :: Defaultable a -> Defaultable a -> Bool Source # (/=) :: Defaultable a -> Defaultable a -> Bool Source # | |
catMaybes :: [Maybe a] -> [a] Source #
The catMaybes function takes a list of Maybes and returns
a list of all the Just values.
Examples
Basic usage:
>>>catMaybes [Just 1, Nothing, Just 3][1,3]
When constructing a list of Maybe values, catMaybes can be used
to return all of the "success" results (if the list is the result
of a map, then mapMaybe would be more appropriate):
>>>import GHC.Internal.Text.Read ( readMaybe )>>>[readMaybe x :: Maybe Int | x <- ["1", "Foo", "3"] ][Just 1,Nothing,Just 3]>>>catMaybes $ [readMaybe x :: Maybe Int | x <- ["1", "Foo", "3"] ][1,3]
Explicit representation of Haskell datatype information
module Text.XML.HaXml.TypeMapping
Types useful for some content models
The List1 type represents lists with at least one element. It is required for DTD content models that use + as a modifier.
Constructors
| NonEmpty [a] |
data ANYContent Source #
A type corresponding to XML's ANY contentspec.
It is either a list of unconverted xml Content
or some XmlContent-able value.
Parsing functions (e.g. parseContents) will always produce UnConverted.
Note: The Show instance for UnConverted uses verbatim.
Constructors
| (XmlContent a, Show a) => ANYContent a | |
| UnConverted [Content Posn] |
Instances
| HTypeable ANYContent Source # | |
Defined in Text.XML.HaXml.XmlContent.Parser Methods toHType :: ANYContent -> HType Source # | |
| XmlContent ANYContent Source # | |
Defined in Text.XML.HaXml.XmlContent.Parser Methods parseContents :: XMLParser ANYContent Source # toContents :: ANYContent -> [Content ()] Source # xToChar :: ANYContent -> Char Source # xFromChar :: Char -> ANYContent Source # | |
| Show ANYContent Source # | |
Defined in Text.XML.HaXml.XmlContent.Parser | |
| Eq ANYContent Source # | |
Defined in Text.XML.HaXml.XmlContent.Parser Methods (==) :: ANYContent -> ANYContent -> Bool Source # (/=) :: ANYContent -> ANYContent -> Bool Source # | |