Initial data commit

Task/Abstract-type/Common-Lisp/abstract-type-1.lisp

@@ -0,0 +1,13 @@
+(defgeneric kar (kons)
+  (:documentation "Return the kar of a kons."))
+
+(defgeneric kdr (kons)
+  (:documentation "Return the kdr of a kons."))
+
+(defun konsp (object &aux (args (list object)))
+  "True if there are applicable methods for kar and kdr on object."
+  (not (or (endp (compute-applicable-methods #'kar args))
+           (endp (compute-applicable-methods #'kdr args)))))
+
+(deftype kons ()
+  '(satisfies konsp))

Task/Abstract-type/Common-Lisp/abstract-type-2.lisp

@@ -0,0 +1,10 @@
+(defmethod kar ((cons cons))
+  (car cons))
+
+(defmethod kdr ((cons cons))
+  (cdr cons))
+
+(konsp (cons 1 2))       ; => t
+(typep (cons 1 2) 'kons) ; => t
+(kar (cons 1 2))         ; => 1
+(kdr (cons 1 2))         ; => 2

Task/Abstract-type/Common-Lisp/abstract-type-3.lisp

@@ -0,0 +1,11 @@
+(defmethod kar ((n integer))
+  1)
+
+(defmethod kdr ((n integer))
+  (if (zerop n) nil
+    (1- n)))
+
+(konsp 45)         ; => t
+(typep 45 'kons)   ; => t
+(kar 45)           ; => 1
+(kdr 45)           ; => 44