2 Even Fibonacci Numbers

1 files changed, 19 insertions, 0 deletions

diff --git a/0002/main.lisp b/0002/main.lisp
new file mode 100644
index 0000000..df3e1cd
--- /dev/null
+++ b/0002/main.lisp
@@ -0,0 +1,19 @@
+(defun new-next-fibo-generator ()
+  (let ((x0 0)
+	(x1 1))
+    (lambda ()
+      (let ((next (+ x0 x1)))
+	(setf x0 x1)
+	(setf x1 next)
+	next))))
+
+(defvar *uplimit* 4000000)
+
+(let ((next-fibo (new-next-fibo-generator))
+      (sum 0))
+  (do ((x (funcall next-fibo) (funcall next-fibo)))
+      ((> x *uplimit*) sum)
+    (setf sum (if (evenp x)
+		  (+ sum x)
+		  sum)))
+  (format t "~&~S" sum))