(defpackage #:phoe-toolbox/list-of (:use))

(deftype list-of (type)
  "A type specifier that matches a list whose all elements are of the given
type."
  (check-type type symbol) ; Kludge - maybe we'll fix that later.
  (let* ((package-name (package-name (symbol-package type)))
         (symbol-name (symbol-name type))
         (predicate-name (format nil "LIST-OF ~S ~S" package-name symbol-name))
         (package (find-package '#:phoe-toolbox/list-of))
         (predicate (intern predicate-name package)))
    (unless (fboundp predicate)
      (setf (fdefinition predicate)
            (lambda (list) (every (rcurry #'typep type) list))))
    `(satisfies ,predicate)))