CL version of destroy for Shen

cl-destroy.shen

\* This script is aimed to run on Shen 7.1 on any Common Lisp port *\

(package cl-destroy- [destroy-it]
(define simple-retract
  X Vec -> (let Pos (hash X (limit Vec))
                (vector-> Vec Pos (fail))))

(define retract
  X Vec -> (let Pos (hash X (limit Vec))
                Content (trap-error (<-vector Vec Pos) (/. (protect E) (error "no vector element to rectract")))
                (do (vector-> Vec Pos (fail))
                    Content)))

\* (declare F []) yields a change-arity error *\
(define shen-destroy-help
  X -> (error "~A is defined as a system function~%" X) where (element? X (value shen-*system*))
  X -> (let Tables [shen-*property-vector*]
            Lists [shen-*tracking* shen-*signedfuncs*]
         (do
           (map (/. Z (simple-retract X (value Z))) Tables)
           (map (/. Z (set Z (remove X (value Z)))) Lists) X)))

\* in CL *\
(define destroy-it
  X -> (do (trap-error (shen-destroy-help X) (/. E E))
           ((protect FMAKUNBOUND) X)
           X)))

\* in JS *\
\* delete window.fn; // as delete works for object properties *\