Thanks, yeah ok, it hadn't occurred to me that cons-stream has to be a macro. I also remember the book also explaining how force and delay work in terms of wra

Thanks, yeah ok, it hadn't occurred to me that cons-stream has to be a macro. I also remember the book also explaining how force and delay work in terms of wrapping and later evaluating a lambda, but don't remember if it explained that delay has to be a macro too. I guess the Common Lisp approach to macro hygiene is using gensyms for temporaries, but Schemers saw that as too ugly. I wonder how Clojure does it. I'm not that big on Scheme or Lisp these days anyway though.