Is it possible to open file then load slime automatically?

Question

So I start up emacs open foo.lisp then I would start slime and the window splits nicely. Except I don't want to start slime manually.

So is it possible to switch to or startup slime when I open an appropriate file?

Such that my file buffer splits and slime is to the side below whatever.

(defun start-or-switch-to (function buffer-name)
  (if (not (get-buffer buffer-name))
      (progn
        (split-window-sensibly (selected-window))
        (other-window 1)
        (funcall function))
    (switch-to-buffer-other-window buffer-name)))

I have found this snippet of code. And tried to execute it with a

(add-hook.....)

This however shoves the opened file and opens slime on both sides of the split.

Answer 1

Using (slime) by itself already splits the buffer, so a separate function to split the buffer is unneeded. By itself it's a one-liner, but to avoid annoying questions and unintended restarts, we need one more statement to check if a slime process is already running:

(add-hook 'lisp-mode-hook '(lambda () 
                              (unless (get-process "SLIME Lisp")
                                (slime))))

Works for me at both start-up and in the middle of a session. If you don't want the cursor to bounce to the REPL, you can use

(add-hook 'lisp-mode-hook '(lambda ()
                                  (unless (get-process "SLIME Lisp")
                                     (let ((oldbuff (current-buffer)))
                                       (slime)
                                       (switch-buffer oldbuff))))