Pact formal verification example

verification.pact

;;
;; A little example showing off the merits of formal
;; verification and why it pays off.
;;

;; Keysets cannot be created in code, thus we read them in
;; from the load message data.
(define-keyset 'admin-keyset (read-keyset "admin-keyset"))

;; Define the module.
(module verification 'admin-keyset
  @doc "Little example to show off the usefulness of formal verification."

  (defun absBug:integer (num:integer)
     @doc "Ensure positive result"
     ;; This property fails: Would you have caught that with unit tests?
     @model [(property (>= result 0))]
     (if (= (- (* (- num 6) (+ num 11)) (* 42 num)) (* (* 64 7) 52270780833))
         (- 1)
         (abs num)
     )
   )
 )