GraphRewriting.Rule

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.

For rule construction a few functions a provided: The most basic one is rewrite. But in most cases erase, 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.

Documentation

data Replace n a

Instances

Monad (Replace n)

Functor (Replace n)

Applicative (Replace n)

Monoid (Replace n ())

type Rule n = Pattern n (Rewrite n ())

A rewriting rule is defined as a Pattern that returns a Rewrite

apply :: Rule n -> Rewrite n ()

Apply rule at an arbitrary position if applicable

apply' :: Rule n -> Rewrite n Bool

Apply rule at an arbitrary position. Return value states whether the rule was applicable.

rewrite :: (Match -> Rewrite n a) -> Rule n

primitive rule construction with the matched nodes of the left hand side as a parameter

erase :: View [Port] n => Rule n

constructs a rule that deletes all of the matched nodes from the graph

rewire :: View [Port] n => [[Edge]] -> Rule n

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.

replace :: View [Port] n => Replace n () -> Rule n

byNode :: (View [Port] n, View v n) => v -> Replace n ()

byNewNode :: View [Port] n => n -> Replace n ()

byEdge :: Replace n Edge

byWire :: Edge -> Edge -> Replace n ()

byConnector :: [Edge] -> Replace n ()

(>>>) :: Rule n -> Rule n -> Rule n

Apply two rules consecutively. Second rule is only applied if first one succeeds. Fails if (and only if) first rule fails.

exhaustive :: Rule n -> Rule n

Make a rule exhaustive, i.e. such that (when applied) it reduces redexes until no redexes are occur in the graph.

everywhere :: Rule n -> Rule n

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.

benchmark :: [Rule n] -> Rewrite n [Int]

Repeatedly apply the rules from the given list prefering earlier entries. Returns a list of indexes reporting the sequence of rules that has applied.