pulled in lisp koans for solving

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

lisp-koans/koans/iteration.lisp

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+;;; 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.
+
+;;; Lisp has multiple options for iteration.
+;;; This set of koans will introduce some of the most common ones.
+
+(define-test dolist
+  (let ((numbers '(4 8 15 16 23 42)))
+    ;; The macro DOLIST binds a variable to subsequent elements of a list.
+    (let ((sum 0))
+      (dolist (number numbers)
+        ;; (INCF PLACE N) is equivalent to (SETF PLACE (+ N PLACE)).
+        (incf sum number))
+      (assert-equal ____ sum))
+    ;; DOLIST can optionally return a value.
+    (let ((sum 0))
+      (assert-equal ____ (dolist (number numbers sum)
+                           (incf sum number))))))
+
+(define-test dotimes
+  ;; The macro DOTIMES binds a variable to subsequent integers from 0 to
+  ;; (1- COUNT).
+  (let ((stack '()))
+    (dotimes (i 5)
+      (push i stack))
+    (assert-equal ____ stack))
+  ;; DOTIMES can optionally return a value.
+  (let ((stack '()))
+    (assert-equal ____ (dotimes (i 5 stack)
+                         (push i stack)))))
+
+(define-test do
+  ;; The macro DO accepts a list of variable bindings, a termination test with
+  ;; epilogue forms, and Lisp code that should be executed on each iteration.
+  (let ((result '()))
+    (do ((i 0 (1+ i)))
+        ((> i 5))
+      (push i result))
+    (assert-equal ____ result))
+  ;; The epilogue of DO can return a value.
+  (let ((result (do ((i 0 (1+ i))
+                     ;; A variable bound by DO noes not need to be updated on
+                     ;; each iteration.
+                     (result '()))
+                    ((> i 5) (nreverse result))
+                  (push i result))))
+    (assert-equal ____ result)))
+
+(define-test loop-basic-form
+  ;; The macro LOOP in its simple form loops forever. It is possible to stop the
+  ;; looping by calling the RETURN special form.
+  (let ((counter 0))
+    (loop (incf counter)
+          (when (>= counter 100)
+            (return counter)))
+    (assert-equal ____ counter))
+  ;; The RETURN special form can return a value out of a LOOP.
+  (let ((counter 0))
+    (assert-equal ____ (loop (incf counter)
+                             (when (>= counter 100)
+                               (return counter)))))
+  ;; The extended form of LOOP will be contemplated in a future koan.
+  )
+