The Emacs Lisp interpreter’s integration with Emacs is pervasive. One can evaluate Emacs Lisp just about everywhere in so many different ways. One way I find particularly handy (especially for short snippets of code) is evaluating Emacs Lisp directly in the minibuffer. This is done with M-: (bound to the command eval-expression).

Upon typing this magic keycombo you’ll be presented with the prompt Eval: in the minibuffer and there you can enter any Lisp expression. Hitting Return will result in the expression’s evaluation.

There is one minor snafu with this, though - I’m addicted to Paredit (for editing Lisp code at least) and Paredit is not automatically enabled in the minibuffer. Let’s change that:

(defun er-conditionally-enable-paredit-mode ()
  "Enable `paredit-mode' in the minibuffer, during `eval-expression'."
  (if (eq this-command 'eval-expression)
      (paredit-mode 1)))

(add-hook 'minibuffer-setup-hook 'er-conditionally-enable-paredit-mode)

Evaluate this snippet and try M-: again. If you’re like me - the results will please you.

It should come as no surprise that Prelude enables Paredit by default for eval-expression.