swish- A semantic web toolkit.

Copyright(c) 2003, Graham Klyne, 2009 Vasili I Galchin, 2011, 2012 Douglas Burke
LicenseGPL V2
MaintainerDouglas Burke
PortabilityCPP, DeriveFunctor, DeriveFoldable, DeriveTraversable, MultiParamTypeClasses
Safe HaskellSafe-Inferred



This module defines a Labelled Directed Graph and Label classes, and the Arc datatype.



class LDGraph lg lb where Source

Labelled Directed Graph class.

Minimum required implementation: emptyGraph, setArcs, and getArcs.

Minimal complete definition

emptyGraph, setArcs, getArcs


emptyGraph :: lg lb Source

Create the empty graph.

setArcs :: lg lb -> ArcSet lb -> lg lb Source

Replace the existing arcs in the graph.

getArcs :: lg lb -> ArcSet lb Source

Extract all the arcs from a graph

extract :: Ord lb => Selector lb -> lg lb -> lg lb Source

Extract those arcs that match the given Selector.

addGraphs :: Ord lb => lg lb -> lg lb -> lg lb Source

Add the two graphs

delete Source


:: Ord lb 
=> lg lb


-> lg lb


-> lg lb

g2 - g1 -> g3

Remove those arcs in the first graph from the second graph

labels :: Ord lb => lg lb -> Set lb Source

Enumerate the distinct labels contained in a graph; that is, any label that appears in the subject, predicate or object position of an Arc.

nodes :: Ord lb => lg lb -> Set lb Source

Enumerate the distinct nodes contained in a graph; that is, any label that appears in the subject or object position of an Arc.

update :: (ArcSet lb -> ArcSet lb) -> lg lb -> lg lb Source

Update the arcs in a graph using a supplied function.


Label lb => LDGraph GraphMem lb 
Label lb => LDGraph NSGraph lb 

class (Ord lb, Show lb) => Label lb where Source

Label class.

A label may have a fixed binding, which means that the label identifies (is) a particular graph node, and different such labels are always distinct nodes. Alternatively, a label may be unbound (variable), which means that it is a placeholder for an unknown node label. Unbound node labels are used as graph-local identifiers for indicating when the same node appears in several arcs.

For the purposes of graph-isomorphism testing, fixed labels are matched when they are the same. Variable labels may be matched with any other variable label. Our definition of isomorphism (for RDF graphs) does not match variable labels with fixed labels.


labelIsVar :: lb -> Bool Source

Does this node have a variable binding?

labelHash :: Int -> lb -> Int Source

Calculate the hash of the label using the supplied seed.

getLocal :: lb -> String Source

Extract the local id from a variable node.

makeLabel :: String -> lb Source

Make a label value from a local id.

data Arc lb Source

Arc type.

Prior to you could also use asubj, apred and aobj to access the elements of the arc.




arcSubj :: lb

The subject of the arc.

arcPred :: lb

The predicate (property) of the arc.

arcObj :: lb

The object of the arc.


Functor Arc 
Foldable Arc 
Traversable Arc 
Eq lb => Eq (Arc lb) 
Ord lb => Ord (Arc lb) 
Show lb => Show (Arc lb) 
Hashable lb => Hashable (Arc lb) 

type ArcSet lb = Set (Arc lb) Source

A set - or graph - of arcs.

type Selector lb = Arc lb -> Bool Source

Identify arcs.

arc Source


:: lb

The subject of the arc.

-> lb

The predicate of the arc.

-> lb

The object of the arc.

-> Arc lb 

Create an arc.

arcToTriple :: Arc lb -> (lb, lb, lb) Source

Convert an Arc into a tuple.

arcFromTriple :: (lb, lb, lb) -> Arc lb Source

Create an Arc from a tuple.

hasLabel :: Eq lb => lb -> Arc lb -> Bool Source

Does the arc contain the label in any position (subject, predicate, or object)?

arcLabels :: Arc lb -> [lb] Source

Return all the labels in an arc.

getComponents :: (Ord a, Ord b) => (a -> [b]) -> Set a -> Set b Source

Extract components from a set.