pulled in lisp koans for solving

https://github.com/google/lisp-koans

lisp-koans/koans/multiple-values.lisp

@@ -0,0 +1,41 @@
+;;; Copyright 2013 Google Inc.
+;;;
+;;; Licensed under the Apache License, Version 2.0 (the "License");
+;;; you may not use this file except in compliance with the License.
+;;; You may obtain a copy of the License at
+;;;
+;;;     http://www.apache.org/licenses/LICENSE-2.0
+;;;
+;;; Unless required by applicable law or agreed to in writing, software
+;;; distributed under the License is distributed on an "AS IS" BASIS,
+;;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+;;; See the License for the specific language governing permissions and
+;;; limitations under the License.
+
+;;; In Lisp, it is possible for a function to return more than one value.
+;;; This is distinct from returning a list or structure of values.
+
+(define-test multiple-values
+  (let ((x (floor 3/2))
+        ;; The macro MULTIPLE-VALUE-LIST returns a list of all values returned
+        ;; by a Lisp form.
+        (y (multiple-value-list (floor 3/2))))
+    (assert-equal x 1)
+    (assert-equal y '(1 1/2)))
+  (assert-equal ____ (multiple-value-list (floor 99/4))))
+
+(defun next-fib (a b)
+  ;; The function VALUES allows returning multiple values.
+  (values b (+ a b)))
+
+(define-test binding-and-setting-multiple-values
+  ;; The macro MULTIPLE-VALUE-BIND is like LET, except it binds the variables
+  ;; listed in its first argument to the values returned by the form that is its
+  ;; second argument.
+  (multiple-value-bind (x y) (next-fib 3 5)
+    (let ((result (* x y)))
+      (assert-equal ____ result)))
+  ;; SETF can also set multiple values if a VALUES form is provided as a place.
+  (let (x y)
+    (setf (values x y) (next-fib 5 8))
+    (assert-equal ____ (list x y))))