Safe Haskell | None |
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The Core module provides the fundamental types, type classes, and functions of the library.
- class RdfParser p where
- parseString :: forall rdf. RDF rdf => p -> Text -> Either ParseFailure rdf
- parseFile :: forall rdf. RDF rdf => p -> String -> IO (Either ParseFailure rdf)
- parseURL :: forall rdf. RDF rdf => p -> String -> IO (Either ParseFailure rdf)
- class RdfSerializer s where
- hWriteRdf :: forall rdf. RDF rdf => s -> Handle -> rdf -> IO ()
- writeRdf :: forall rdf. RDF rdf => s -> rdf -> IO ()
- hWriteH :: forall rdf. RDF rdf => s -> Handle -> rdf -> IO ()
- writeH :: forall rdf. RDF rdf => s -> rdf -> IO ()
- hWriteTs :: s -> Handle -> Triples -> IO ()
- writeTs :: s -> Triples -> IO ()
- hWriteT :: s -> Handle -> Triple -> IO ()
- writeT :: s -> Triple -> IO ()
- hWriteN :: s -> Handle -> Node -> IO ()
- writeN :: s -> Node -> IO ()
- class RDF rdf where
- baseUrl :: rdf -> Maybe BaseUrl
- prefixMappings :: rdf -> PrefixMappings
- addPrefixMappings :: rdf -> PrefixMappings -> Bool -> rdf
- empty :: rdf
- mkRdf :: Triples -> Maybe BaseUrl -> PrefixMappings -> rdf
- triplesOf :: rdf -> Triples
- select :: rdf -> NodeSelector -> NodeSelector -> NodeSelector -> Triples
- query :: rdf -> Maybe Node -> Maybe Node -> Maybe Node -> Triples
- data Triple = Triple !Node !Node !Node
- triple :: Subject -> Predicate -> Object -> Triple
- type Triples = [Triple]
- sortTriples :: Triples -> Triples
- data Node
- data LValue
- newtype BaseUrl = BaseUrl Text
- newtype PrefixMappings = PrefixMappings (Map Text Text)
- toPMList :: PrefixMappings -> [(Text, Text)]
- newtype PrefixMapping = PrefixMapping (Text, Text)
- type NodeSelector = Maybe (Node -> Bool)
- isUNode :: Node -> Bool
- isBNode :: Node -> Bool
- isLNode :: Node -> Bool
- equalSubjects :: Triple -> Triple -> Bool
- equalPredicates :: Triple -> Triple -> Bool
- equalObjects :: Triple -> Triple -> Bool
- isIsomorphic :: forall rdf1 rdf2. (RDF rdf1, RDF rdf2) => rdf1 -> rdf2 -> Bool
- subjectOf :: Triple -> Node
- predicateOf :: Triple -> Node
- objectOf :: Triple -> Node
- isEmpty :: RDF rdf => rdf -> Bool
- rdfContainsNode :: forall rdf. RDF rdf => rdf -> Node -> Bool
- tripleContainsNode :: Node -> Triple -> Bool
- listSubjectsWithPredicate :: RDF rdf => rdf -> Predicate -> [Subject]
- listObjectsOfPredicate :: RDF rdf => rdf -> Predicate -> [Object]
- type Subject = Node
- type Predicate = Node
- type Object = Node
- newtype ParseFailure = ParseFailure String
- s2t :: String -> Text
- t2s :: Text -> String
- unode :: Text -> Node
- bnode :: Text -> Node
- lnode :: LValue -> Node
- plainL :: Text -> LValue
- plainLL :: Text -> Text -> LValue
- typedL :: Text -> Text -> LValue
- class View a b where
- view :: a -> b
- fromEither :: RDF rdf => Either ParseFailure rdf -> rdf
- removeDupes :: Triples -> Triples
Parsing RDF
An RdfParser is a parser that knows how to parse 1 format of RDF and can parse an RDF document of that type from a string, a file, or a URL. Required configuration options will vary from instance to instance.
parseString :: forall rdf. RDF rdf => p -> Text -> Either ParseFailure rdfSource
Parse RDF from the given bytestring, yielding a failure with error message or the resultant RDF.
parseFile :: forall rdf. RDF rdf => p -> String -> IO (Either ParseFailure rdf)Source
Parse RDF from the local file with the given path, yielding a failure with error message or the resultant RDF in the IO monad.
parseURL :: forall rdf. RDF rdf => p -> String -> IO (Either ParseFailure rdf)Source
Parse RDF from the remote file with the given HTTP URL (https is not supported), yielding a failure with error message or the resultant graph in the IO monad.
RdfParser TurtleParser |
|
RdfParser NTriplesParser |
|
Serializing RDF
class RdfSerializer s whereSource
An RdfSerializer is a serializer of RDF to some particular output format, such as NTriples or Turtle.
hWriteRdf :: forall rdf. RDF rdf => s -> Handle -> rdf -> IO ()Source
Write the RDF to a file handle using whatever configuration is specified by the first argument.
writeRdf :: forall rdf. RDF rdf => s -> rdf -> IO ()Source
Write the RDF to stdout; equivalent to
.
hWriteRdf
stdout
hWriteH :: forall rdf. RDF rdf => s -> Handle -> rdf -> IO ()Source
Write to the file handle whatever header information is required based on the output format. For example, if serializing to Turtle, this method would write the necessary @prefix declarations and possibly a @baseUrl declaration, whereas for NTriples, there is no header section at all, so this would be a no-op.
writeH :: forall rdf. RDF rdf => s -> rdf -> IO ()Source
Write header information to stdout; equivalent to
.
hWriteRdf
stdout
hWriteTs :: s -> Handle -> Triples -> IO ()Source
Write some triples to a file handle using whatever configuration is specified by the first argument.
WARNING: if the serialization format has header-level information
that should be output (e.g., @prefix declarations for Turtle), then you should
use hWriteG
instead of this method unless you're sure this is safe to use, since
otherwise the resultant document will be missing the header information and
will not be valid.
writeTs :: s -> Triples -> IO ()Source
Write some triples to stdout; equivalent to
.
hWriteTs
stdout
hWriteT :: s -> Handle -> Triple -> IO ()Source
Write a single triple to the file handle using whatever configuration is
specified by the first argument. The same WARNING applies as to hWriteTs
.
writeT :: s -> Triple -> IO ()Source
Write a single triple to stdout; equivalent to
.
hWriteT
stdout
hWriteN :: s -> Handle -> Node -> IO ()Source
Write a single node to the file handle using whatever configuration is
specified by the first argument. The same WARNING applies as to hWriteTs
.
writeN :: s -> Node -> IO ()Source
Write a single node to sdout; equivalent to
.
hWriteN
stdout
RDF type
An RDF value is a set of (unique) RDF triples, together with the operations defined upon them.
For information about the efficiency of the functions, see the documentation for the particular RDF instance.
For more information about the concept of an RDF graph, see the following: http://www.w3.org/TR/rdf-concepts/#section-rdf-graph.
baseUrl :: rdf -> Maybe BaseUrlSource
Return the base URL of this RDF, if any.
prefixMappings :: rdf -> PrefixMappingsSource
Return the prefix mappings defined for this RDF, if any.
addPrefixMappings :: rdf -> PrefixMappings -> Bool -> rdfSource
Return an RDF with the specified prefix mappings merged with the existing mappings. If the Bool arg is True, then a new mapping for an existing prefix will replace the old mapping; otherwise, the new mapping is ignored.
Return an empty RDF.
mkRdf :: Triples -> Maybe BaseUrl -> PrefixMappings -> rdfSource
Return a RDF containing all the given triples. Handling of duplicates in the input depend on the particular RDF implementation.
triplesOf :: rdf -> TriplesSource
Return all triples in the RDF, as a list.
select :: rdf -> NodeSelector -> NodeSelector -> NodeSelector -> TriplesSource
Select the triples in the RDF that match the given selectors.
The three NodeSelector parameters are optional functions that match
the respective subject, predicate, and object of a triple. The triples
returned are those in the given graph for which the first selector
returns true when called on the subject, the second selector returns
true when called on the predicate, and the third selector returns true
when called on the ojbect. A Nothing
parameter is equivalent to a
function that always returns true for the appropriate node; but
implementations may be able to much more efficiently answer a select
that involves a Nothing
parameter rather than an (id True)
parameter.
The following call illustrates the use of select, and would result in the selection of all and only the triples that have a blank node as subject and a literal node as object:
select gr (Just isBNode) Nothing (Just isLNode)
Note: this function may be very slow; see the documentation for the particular RDF implementation for more information.
query :: rdf -> Maybe Node -> Maybe Node -> Maybe Node -> TriplesSource
Return the triples in the RDF that match the given pattern, where the pattern (3 Maybe Node parameters) is interpreted as a triple pattern.
The Maybe Node
params are interpreted as the subject, predicate, and
object of a triple, respectively. Just n
is true iff the triple has
a node equal to n
in the appropriate location; Nothing
is always
true, regardless of the node in the appropriate location.
For example, query rdf (Just n1) Nothing (Just n2)
would return all
and only the triples that have n1
as subject and n2
as object,
regardless of the predicate of the triple.
RDF triples, nodes, and literals
An RDF triple is a statement consisting of a subject, predicate, and object, respectively.
See http://www.w3.org/TR/rdf-concepts/#section-triples for more information.
sortTriples :: Triples -> TriplesSource
Answer the given list of triples in sorted order.
An RDF node, which may be either a URIRef node (UNode
), a blank
node (BNode
), or a literal node (LNode
).
UNode !Text | An RDF URI reference. See http://www.w3.org/TR/rdf-concepts/#section-Graph-URIref for more information. |
BNode !Text | An RDF blank node. See http://www.w3.org/TR/rdf-concepts/#section-blank-nodes for more information. |
BNodeGen !Int | An RDF blank node with an auto-generated identifier, as used in Turtle. |
LNode !LValue | An RDF literal. See http://www.w3.org/TR/rdf-concepts/#section-Graph-Literal for more information. |
Eq Node | A node is equal to another node if they are both the same type of node and if the field values are equal. |
Ord Node | Node ordering is defined first by type, with Unode < BNode < BNodeGen < LNode PlainL < LNode PlainLL < LNode TypedL, and secondly by the natural ordering of the node value. E.g., a '(UNode _)' is LT any other type of node, and a '(LNode (TypedL _ _))' is GT any other type of node, and the ordering of '(BNodeGen 44)' and '(BNodeGen 3)' is that of the values, or 'compare 44 3', GT. |
Show Node |
PlainL !Text | A plain (untyped) literal value in an unspecified language. |
PlainLL !Text !Text | A plain (untyped) literal value with a language specifier. |
TypedL !Text !Text | A typed literal value consisting of the literal value and the URI of the datatype of the value, respectively. |
Eq LValue | Two |
Ord LValue | Ordering of |
Show LValue |
Supporting types and functions
newtype PrefixMappings Source
An alias for a map from prefix to namespace URI.
PrefixMappings (Map Text Text) |
toPMList :: PrefixMappings -> [(Text, Text)]Source
View the prefix mappings as a list of key-value pairs. The PM in in the name is to reduce name clashes if used without qualifying.
newtype PrefixMapping Source
A mapping of a prefix to the URI for that prefix.
PrefixMapping (Text, Text) |
type NodeSelector = Maybe (Node -> Bool)Source
A NodeSelector
is either a function that returns True
or False
for a node, or Nothing, which indicates that all
nodes would return True
.
The selector is said to select, or match, the nodes for
which it returns True
.
When used in conjunction with the select
method of Graph
, three
node selectors are used to match a triple.
equalSubjects :: Triple -> Triple -> BoolSource
Determine whether two triples have equal subjects.
equalPredicates :: Triple -> Triple -> BoolSource
Determine whether two triples have equal predicates.
equalObjects :: Triple -> Triple -> BoolSource
Determine whether two triples have equal objects.
isIsomorphic :: forall rdf1 rdf2. (RDF rdf1, RDF rdf2) => rdf1 -> rdf2 -> BoolSource
This determines if two RDF representations are equal regardless of blank nodc names, triple order and prefixes. In math terms, this is the simeq latex operator, or ~=
predicateOf :: Triple -> NodeSource
Answer the predicate node of the triple.
rdfContainsNode :: forall rdf. RDF rdf => rdf -> Node -> BoolSource
Answer if rdf contains node.
tripleContainsNode :: Node -> Triple -> BoolSource
Answer if triple contains node.
listSubjectsWithPredicate :: RDF rdf => rdf -> Predicate -> [Subject]Source
Lists of all subjects of triples with the given predicate.
listObjectsOfPredicate :: RDF rdf => rdf -> Predicate -> [Object]Source
Lists of all objects of triples with the given predicate.
newtype ParseFailure Source
Represents a failure in parsing an N-Triples document, including an error message with information about the cause for the failure.
plainLL :: Text -> Text -> LValueSource
Return a PlainLL LValue for the given string value and language, respectively.
typedL :: Text -> Text -> LValueSource
Return a TypedL LValue for the given string value and datatype URI, respectively.
fromEither :: RDF rdf => Either ParseFailure rdf -> rdfSource
Convert a parse result into an RDF if it was successful and error and terminate if not.
removeDupes :: Triples -> TriplesSource
Remove duplicate triples, returning unique triples. This function may return the triples in a different order than given.