Quickly set up a LISP IDE with Emacs

Install a LISP compiler. We’ll use Steel Bank Common Lisp. Extract the downloaded archive and run install.sh. If the binary location is not /opt/sbcl/bin/sbcl note it.
Install emacs sudo apt-get install emacs
Set up the MELPA repository adding this to your ~/.emacs file
```
(require 'package) ;; You might already have this line
```

(add-to-list ‘package-archives ‘(“melpa” . “https://melpa.org/packages/")) (when (< emacs-major-version 24) ;; For important compatibility libraries like cl-lib (add-to-list ‘package-archives ‘(“gnu” . “http://elpa.gnu.org/packages/"))) (package-initialize) ;; You might already have this line

- Install SLIME with <code> M-x package-install RET slime RET </code>
- Set up SLIME and the LISP compiler location in the <code>~/.emacs</code> file
```emacs-lisp
;; Set your lisp system and, optionally, some contribs
(setq inferior-lisp-program "/opt/sbcl/bin/sbcl")
(slime-setup '(slime-fancy))

Additionaly, this adds an hook that starts SLIME when you open a lisp file

(add-hook 'slime-mode-hook
          (lambda ()
            (unless (slime-connected-p)

(defun my-slime-setup ()
  (require 'slime)
  (slime-setup '(slime-fancy)))
(defvar my--slime-setup-done nil)
(defun my-slime-setup-once ()
  (unless my--slime-setup-done
    (my-slime-setup)
    (setq my--slime-setup-done t)))
(defadvice lisp-mode (before my-slime-setup-once activate)
  (my-slime-setup-once))

(my-slime-setup)

Finally, run M-x slime. It will compile the backend and finally give you the prompt.