Labelled Directed Graph class
-Minimum required implementation: `setArcs`, `getArcs` and `containedIn`
-(although @containedIn@ may be removed as it is currently unused).
+Minimum required implementation: `setArcs` and `getArcs`.
class (Eq (lg lb), Eq lb ) => LDGraph lg lb
nodes g = foldl' union  (map arcNodes (getArcs g))
- -- | Test for graph containment in another.
- -- At present this is unused and may be removed in a future release.
- containedIn :: lg lb -> lg lb -> Bool
-- | Update the arcs in a graph using a supplied function.
update :: ( [Arc lb] -> [Arc lb] ) -> lg lb -> lg lb
update f g = setArcs ( f (getArcs g) ) g