Slotted terms is a highly valuable feature of languages like F-Logic, standards (RIF or RuleML), and products (like OO-jDREW). They also make interoperability with forward-chaining rule systems like JBoss Rules far easier.
Prova 3.0 includes an implementation of slotted terms using the W3C RIF arrow expression syntax as in the following example map2.prova. Note that Prova also allows to use colon ':' in key:value instead of key->value. The keys are currently limited to strings.
This shows that Prova maps can be used as sole arguments of predicates, essentially replacing position-based syntax with one based on named arguments. The example prints:
The test map2() in ProvaBuiltins1Test.java is based on this example.
Slotted terms are especially useful in reactive messaging, see the discussion on Using slotted terms (Prova maps) in reactive messaging.