types.lisp

   1 (in-package :alexandria)
   2
   3 (declaim (inline of-type))
   4 (defun of-type (type)
   5   "Returns a function of one argument, which returns true when its argument is
   6 of TYPE."
   7   (lambda (thing) (typep thing type)))
   8
   9 (declaim (inline type=))
  10 (defun type= (type1 type2)
  11   "Returns a primary value of T is TYPE1 and TYPE2 are the same type,
  12 and a secondary value that is true is the type equality could be reliably
  13 determined: primary value of NIL and secondary value of T indicates that the
  14 types are not equivalent."
  15   (multiple-value-bind (sub ok) (subtypep type1 type2)
  16     (cond ((and ok sub)
  17            (subtypep type2 type1))
  18           (ok
  19            (values nil ok))
  20           (t
  21            (multiple-value-bind (sub ok) (subtypep type2 type1)
  22              (declare (ignore sub))
  23              (values nil ok))))))