PPRINT in Emacs Lisp?

Question

Emacs Lisp does not seem to have a PPRINT function. How do you pretty print an S-EXP in elisp the way you can in Common Lisp?

Thanks!

Answer 1

Assuming that the result of cl-prettyprint is good enough for you, here's how to get its output in a stream.

(defun pprint (form &optional output-stream)
  (princ (with-temp-buffer
           (cl-prettyprint form)
           (buffer-string))
         output-stream))

Answer 2

Use the pp library which is part of GNU Emacs. For example you can use pp-macroexpand-last-sexp for prettifying an sexp.