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Error-checking

Ensure-function-arity

Cause an error if a function does not have a given arity.

Signature
(ensure-function-arity fn n description error-erp error-val ctx state) → (mv erp val state)
Arguments: fn — Function to check.
Guard (function-namep fn (w state)).; n — Arity that fn must have.
Guard (natp n).; 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-arity

(defun ensure-function-arity (fn n description
                                 error-erp error-val ctx state)
  (declare (xargs :stobjs (state)))
  (declare (xargs :guard (and (natp n)
                              (msgp description)
                              (function-namep fn (w state)))))
  (b* (((unless (= (arity fn (w state)) n))
        (er-soft+ ctx error-erp error-val
                  "~@0 must take ~x1 ~@2." description
                  n (if (= n 1) "argument" "arguments"))))
    (value nil)))

Theorem: return-type-of-ensure-function-arity.erp

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

Theorem: return-type-of-ensure-function-arity.val

(defthm return-type-of-ensure-function-arity.val
  (b* (((mv ?erp ?val ?state)
        (ensure-function-arity fn n 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-arity$: Calls ensure-function-arity with ctx and state as the last two arguments.