Redland

Redland RDF library bindings. See the original API for in-depth descriptions.

Library organization

• Raw bindings are provided by Redland.LowLevel. Normally they should not be used directly.
• Refined versions (using Haskell types) of those are provided by Redland.MidLevel. One should still be careful with the allocated resources while using those, for instance by using withNew. A rule of thumb is that whenever you see an Initializer, it's a good idea to wrap it into withNew.
• Utility functions and types are provided by Redland.Util. Those don't strictly correspond to functions of the original API.

Usage example

import Redland

input :: String
input = "<?xml version=\"1.0\"?>\
\<rdf:RDF xmlns:rdf=\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\"\
\     xmlns:dc=\"http://purl.org/dc/elements/1.1/\">\
\  <rdf:Description rdf:about=\"http://www.dajobe.org/\">\
\    <dc:title>Dave Beckett's Home Page</dc:title>\
\    <dc:creator>Dave Beckett</dc:creator>\
\    <dc:description>The generic home page of Dave Beckett.</dc:description>\
\  </rdf:Description>\
\</rdf:RDF>\
\"

main :: IO ()
main =
  withWSMU "memory" [] "example" "" "http://example.librdf.org/" $
  \world storage model uri -> do
    -- parse and insert
    guessingParseStringIntoModel world model uri input
    -- query
    withQuery world model "sparql"
      "SELECT ?foo ?bar ?baz WHERE { ?foo ?bar ?baz }" (Just uri) $
      mapM_ print
    -- search statements
    withStatements world model (Triple Nothing Nothing Nothing) $
      mapM_ print

It prints the following:

[("foo",ResourceNode "http://www.dajobe.org/"),("bar",ResourceNode "http://purl.org/dc/elements/1.1/title"),("baz",LiteralNode "Dave Beckett's Home Page" Nothing)]
[("foo",ResourceNode "http://www.dajobe.org/"),("bar",ResourceNode "http://purl.org/dc/elements/1.1/creator"),("baz",LiteralNode "Dave Beckett" Nothing)]
[("foo",ResourceNode "http://www.dajobe.org/"),("bar",ResourceNode "http://purl.org/dc/elements/1.1/description"),("baz",LiteralNode "The generic home page of Dave Beckett." Nothing)]
Triple {subject = Just (ResourceNode "http://www.dajobe.org/"), predicate = Just (ResourceNode "http://purl.org/dc/elements/1.1/title"), object = Just (LiteralNode "Dave Beckett's Home Page" Nothing)}
Triple {subject = Just (ResourceNode "http://www.dajobe.org/"), predicate = Just (ResourceNode "http://purl.org/dc/elements/1.1/creator"), object = Just (LiteralNode "Dave Beckett" Nothing)}
Triple {subject = Just (ResourceNode "http://www.dajobe.org/"), predicate = Just (ResourceNode "http://purl.org/dc/elements/1.1/description"), object = Just (LiteralNode "The generic home page of Dave Beckett." Nothing)}

Documentation

module Redland.MidLevel

module Redland.Util

data RedlandWorld

data RedlandHash

data RedlandModel

data RedlandNode

data RedlandParser

data RedlandQuery

data RedlandQueryResults

data RedlandStatement

data RedlandStorage

data RedlandStream

data RedlandURI

data ForeignPtr a :: * -> *

The type ForeignPtr represents references to objects that are maintained in a foreign language, i.e., that are not part of the data structures usually managed by the Haskell storage manager. The essential difference between ForeignPtrs and vanilla memory references of type Ptr a is that the former may be associated with finalizers. A finalizer is a routine that is invoked when the Haskell storage manager detects that - within the Haskell heap and stack - there are no more references left that are pointing to the ForeignPtr. Typically, the finalizer will, then, invoke routines in the foreign language that free the resources bound by the foreign object.

The ForeignPtr is parameterised in the same way as Ptr. The type argument of ForeignPtr should normally be an instance of class Storable.

Instances

Eq (ForeignPtr a)

Methods

(==) :: ForeignPtr a -> ForeignPtr a -> Bool

(/=) :: ForeignPtr a -> ForeignPtr a -> Bool

Ord (ForeignPtr a)

Methods

compare :: ForeignPtr a -> ForeignPtr a -> Ordering

(<) :: ForeignPtr a -> ForeignPtr a -> Bool

(<=) :: ForeignPtr a -> ForeignPtr a -> Bool

(>) :: ForeignPtr a -> ForeignPtr a -> Bool

(>=) :: ForeignPtr a -> ForeignPtr a -> Bool

max :: ForeignPtr a -> ForeignPtr a -> ForeignPtr a

min :: ForeignPtr a -> ForeignPtr a -> ForeignPtr a

Show (ForeignPtr a)

Methods

showsPrec :: Int -> ForeignPtr a -> ShowS

show :: ForeignPtr a -> String

showList :: [ForeignPtr a] -> ShowS