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Error-checking

Ensure-function-known-measure

Cause an error if a recursive function has an unknown measure (i.e. one with :?).

Signature
(ensure-function-known-measure fn description error-erp error-val ctx state) → (mv erp val state)
Arguments: fn — Function to check.
Guard (and (logic-function-namep fn (w state)) (recursivep fn nil (w state))) .; description — Guard (msgp description).; error-erp — Flag to return in case of error.; error-val — Value to return in case of error.; ctx — Context for errors.
Returns: erp — Type (implies erp (equal erp error-erp)).; val — Type (and (implies erp (equal val error-val)) (implies (and (not erp) error-erp) (not val))) .

Definitions and Theorems

Function: ensure-function-known-measure

(defun ensure-function-known-measure
       (fn description
           error-erp error-val ctx state)
 (declare (xargs :stobjs (state)))
 (declare
      (xargs :guard (and (msgp description)
                         (and (logic-function-namep fn (w state))
                              (recursivep fn nil (w state))))))
 (b*
  (((when (eq (car (measure fn (w state))) :?))
    (er-soft+
     ctx error-erp error-val
     "~@0 must have a known measure, i.e. not one of the form (:? ...)."
     description)))
  (value nil)))

Theorem: return-type-of-ensure-function-known-measure.erp

(defthm return-type-of-ensure-function-known-measure.erp
  (b*
   (((mv ?erp ?val ?state)
     (ensure-function-known-measure fn description
                                    error-erp error-val ctx state)))
   (implies erp (equal erp error-erp)))
  :rule-classes :rewrite)

Theorem: return-type-of-ensure-function-known-measure.val

(defthm return-type-of-ensure-function-known-measure.val
  (b*
   (((mv ?erp ?val ?state)
     (ensure-function-known-measure fn description
                                    error-erp error-val ctx state)))
   (and (implies erp (equal val error-val))
        (implies (and (not erp) error-erp)
                 (not val))))
  :rule-classes :rewrite)

Subtopics

Ensure-function-known-measure$: Calls ensure-function-known-measure with ctx and state as the last two arguments.