Rewrite rules are represented as nested monads: a
Rule is a
Pattern that returns a
Rewrite the latter directly defining the transformation of the graph. The
Rewrite itself is expected to return a list of newly created nodes.
For rule construction a few functions a provided: The most basic one is
rewrite. But in most cases
rewire, and 'replace*' should be more convenient. These functions express rewrites that replace the matched nodes of the
Pattern, which comes quite close to the
L -> R form in which graph rewriting rules are usually expressed.
- type Rule n = Pattern n (Rewrite n [Node])
- rewrite :: (Match -> Rewrite n [Node]) -> Rule n
- erase :: View [Port] n => Rule n
- rewire :: View [Port] n => [[Edge]] -> Rule n
- data RHS v
- replace :: (View [Port] n, View v n) => Int -> ([Edge] -> [RHS v]) -> Rule n
- (>>>) :: Rule n -> Rule n -> Rule n
- exhaustive :: Rule n -> Rule n
- everywhere :: Rule n -> Rule n
- apply :: Rule n -> Rewrite n [Node]
primitive rule construction with the matched nodes of the left hand side as a parameter
constructs a rule that deletes all of the matched nodes from the graph
Constructs a rule from a list of rewirings. Each rewiring specifies a list of hyperedges that are to be merged into a single hyperedge. All matched nodes of the left-hand side are removed.
Constructs a rule that replaces the matched nodes of the left-hand side by new nodes and rewirings. It generates an amount of new edges specified by the
Int. In most cases the functions below named
replace* should be sufficient.
Replaces the matched nodes by a list of new nodes and rewirings.
Replaces the matched nodes by a list of new nodes and rewirings. It also generates one new edge.
Replaces the matched nodes by a list of new nodes and rewirings. It also generates two new edges.
You get the idea.
Apply two rules consecutively. Second rule is only applied if first one succeeds. Fails if (and only if) first rule fails. BUG: what if r2 deletes some of the nodes created in r1? Probably it's a bad idea, that the set of created nodes is returned by the rewrite at all.
Make a rule exhaustive, i.e. such that (when applied) it reduces redexes until no redexes are occur in the graph.
Make a rule parallel, i.e. such that (when applied) all current redexes are contracted one by one. Neither new redexes or destroyed redexes are reduced.