I'm trying to grasp the semantics of call/cc in Scheme, and the Wikipedia page on continuations shows the yin-yang puzzle as an example: (let* ((yin ((lambda (cc) (display #\@) cc) (call-with-current-continuation (lambda (c) c)))) (yang ((lambda (cc) (display #\*) cc) (call-with-current-continuation (lambda (c) c)))) ) (yin yang)) It should output @\*@\**@\**\*@\**\**@..., but I don't understand why; I'd expect it to output @\*@\**\**\**\**\*... Can somebody explain in detail why the yin-yang puzzle works the way it works?