Pretty-printing lists (adding newlines and indent)

[Teemu Likonen]

Is there an easy way to pretty-print lists in Emacs Lisp? I mean adding
newlines and indents like in the inferior-emacs-lisp-mode (M-x ielm):

    ELISP> '((a1 a2) (b1 (1 2 3 4 5)) (c1 c2))
    ((a1 a2)
     (b1
      (1 2 3 4 5))
     (c1 c2))    

I have a potentially big multi-level hierarchical list data which I'd
like to PRIN1 to a buffer. Having the whole list as a single line is
ugly and unreadable.