IELM

IELM (Interactive Emacs Lisp Mode) is a nice mode that gives you an interactive Emacs Lisp shell (or a REPL if you prefer) that you can use for exploratory programming. You can start it by pressing M-x ielm. You'll be taken to a buffer named ielm, where Emacs Lisp expressions you've entered will be evaluated on pressing the Return key. IELM offers some nice features like TAB autocompletion of symbol names and the ability to span an expression over several lines.

Basic setup

IELM is bundled with Emacs by default. No addition setup is required.

Helpful keybindings

[Tab]

Complete symbol at point.

[Return]

Evaluate expression

Common Customization

Show eldoc in IELM

(defun my-ielm-mode-defaults ()
  (turn-on-eldoc-mode))

(setq my-ielm-mode-hook 'my-ielm-mode-defaults)

(add-hook 'ielm-mode-hook (lambda () (run-hooks 'my-ielm-mode-hook)))

Recommended Reading

• Emacs Lisp
• REPL

Tutorial Pages

IELM: A REPL for Emacs