opencog-ure / tests / ure / rules / closed-lambda-introduction-rule.scm

;; =====================================================================
;; Closed lambda introduction rule
;;
;; V
;; Body
;; |-
;; LambdaLink
;;    V
;;    Body
;;
;; Wrap a Lambda around a closed atom (that is an atom without free
;; variables in it) and assign to the lambda the TV of the body. So
;; basically it create a constant predicate or schema.
;; ----------------------------------------------------------------------

(define closed-lambda-introduction-vardecl
  (VariableSet
     (TypedVariableLink
        (VariableNode "$V")
        (TypeChoice
           (TypeNode "TypedVariableLink")
           (TypeNode "VariableSet")
           (TypeNode "VariableList")
           (TypeNode "VariableNode")))
     (VariableNode "$B")))

(define closed-lambda-introduction-pattern
  (AndLink
     (PresentLink
        (VariableNode "$V")
        (VariableNode "$B"))
     (EvaluationLink
        (GroundedPredicateNode "scm-eager: closed-lambda-introduction-precondition")
        (VariableNode "$B"))))

(define closed-lambda-introduction-rewrite
  (ExecutionOutputLink
     (GroundedSchemaNode "scm-eager: closed-lambda-introduction")
     (ListLink
        (QuoteLink (LambdaLink
           (UnquoteLink (VariableNode "$V"))
           (UnquoteLink (VariableNode "$B"))))
        (VariableNode "$B"))))

(define closed-lambda-introduction-rule
  (BindLink
     closed-lambda-introduction-vardecl
     closed-lambda-introduction-pattern
     closed-lambda-introduction-rewrite))

(define (closed-lambda-introduction lamb body)
  (cog-set-tv! lamb (cog-tv body)))

(define (closed-lambda-introduction-precondition atom)
  (bool->tv (and (cog-closed? atom) (< 0 (cog-confidence atom)))))

;; Name the rule
(define closed-lambda-introduction-rule-name
  (DefinedSchemaNode "closed-lambda-introduction-rule"))
(DefineLink closed-lambda-introduction-rule-name
  closed-lambda-introduction-rule)