fogus.reinen-vernunft.datalog — me.fogus/reinen-vernunft 0.0.3

A minimal implementation of Datalog.

q clj

(q query kb)

(q query kb rules)

Queries a knowledge base or a set of relations given a vector form of a query and an optional set of rules.

A query takes the form:

[:find find-spec :where clauses]

A find-spec can be any number of lvars like:

[:find ?e ?v :where ...]

or a tuple containing a mix of lvars and grounds which is used to build output tuples from the query results:

[:find [?e :an/attribute ?v] :where ...]

The :where clauses are any number of tuples containing a mix of lvars and grounds:

[:find ... :where [?e :an/attribute ?v] [?e :another/attr 42]]

:where clauses may also contain filters defined as calls to predicates used to constrain the values that may bind to lvars:

[:find ... :where [?e :an/attribute ?v] (= ?v 42)]

The possible filter predicates are: =, not=, <, >, <=, >=

rules are a vector of lists where each list defines a rule with a single head tuple followed by any number of rule clauses:

([?p :relationship/parent ?c] [?p :relationship/father ?c])

The rule above defines a syntheic relation called :relationship/parent defined in terms of another relation relationship/father. Rules describe synthetic relations derived from real relations in the data or other synthetic relations derived from previous rule applications.

query->map clj

(query->map query)

Accepts the vector form of a Datalog query and outputs a map of the component sections as keyword->seq mappings.