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I once read somewhere, that we can set a global Emacs variable to T (or NIL, I don't know) in order to (roughly) make Emacs accessible from Common Lisp.

This information was in company with the warning, that this might have undesired side effects. I want to avoid that, that's why I just pushed the whole information to my minds /dev/null.

But: Is there a way, to make the slime-repl environment recognisable for the Common Lisp it hosts just in the narrow context of a function?

I would like to write a slime-clear-screen function that preferably re-draws the whole Emacs window like it seems to be the effect of C-c M-o in slime. Alternatively, (format t "~%") is repeated according to the number of lines of the current window size.

So I need to find a way to get access to the Emacs window controls or its size information, I guess.

But I have trouble to hear promising informations in the noise of Slime/Emacs keychord configuration requests and ANSI escape sequences.

Do you know, what I need for that? Or even better: Do you know a public library that already provides an equivalent function? Although I really like to tinker, I also explicitly look for commonly used or recommendable libraries to build-up a consistent framework of open-source "quasi-standard" libraries from the large buffet.

I thank you very much for your suggestions.

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  • Well, I think it is not possible the way I want it. Maybe it would be more recommendable to connect with an external repl and do stuff that should clear the screen say, refresh it, there. Maybe also with cl-ncurses, or cl-readline already provides useful tools. Commented Mar 22 at 9:56
  • Emacs would be a better place to ask this. Commented Mar 22 at 13:59

2 Answers 2

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The variable is slime-enable-evaluate-in-emacs, and if set to T you call eval-in-emacs.

But there is a way to avoid doing so. The Common Lisp side, Swank, uses send-to-emacs to emit messages to the Emacs Lisp side, Slime. This is something like (:my-message x y z). But that must be a valid message, one among some that are recognized by both sides.

In slime.el, there is a hook named slime-event-hooks where you can process custom messages. It is used like this:

(or (run-hooks-with-args-until-success 'slime-event-hooks event)
    (slime-dcase event
      ... ; builtin events
    ))

See for example contrib/slime-media.el where a hook is registered when :on-load happens.

The same mechanism exists on the Lisp side. In swank.lisp, there is a special variable *event-hook* that can contain additional code to run and handle events.

(or (run-hook-until-success *event-hook* connection event)
    (dcase event
      ... ; builtin events
    ))

There is no example in contrib where it is used, as far as I know.

So there is definitely a way to implement a new contrib feature for Slime which doesn't look like a hack, you need to implement your own protocol by registering messages, and then do what you want in Emacs.

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I misunderstood your question and thought you search for a way to clear the screen in a common lisp REPL.

Which command could be used to clear screen in CLISP?

There you find methods like:

(screen:with-window (screen:clear-window screen:*window*))

or

(defun cls()
  (format t "~A[H~@*~A[J" #\escape))

(cls)

That works even on naked terminal CLISP or SBCL (while with SBCL only the latter one). The last one actually prints so many empty lines - that it seems that it is a cleared screen.

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Ah, now I see: "Request clarification" is the new way to go for a normal comment. Thank you as well for your answer :-) Yes, the "clear screen" ASCII sequence crossed my path as well. But yes, I was after the SLIME repl. And I think, sooner or later I cannot help it, I will have to try out @coredumps recommendation. But I think, for now, it becomes more interesting to M-x slime-connect with a SBCL terminal and use cl-charms there. - That was still on the agenda ;-)

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