[slime-devel] Re: Evaluate forms from within Lisp buffers and displaying the result in the REPL

Rainer Joswig joswig at lisp.de
Mon Apr 23 08:17:21 UTC 2007

In article 
<8757cb490704222232m429a62avf02c9225cb2c68fa at mail.gmail.com>,
 "Bill Clementson" <billclem at gmail.com> wrote:

> Hi Marco,
> On 4/20/07, Marco Baringer <mb at bese.it> wrote:
> > "Bill Clementson" <billclem at gmail.com> writes:
> >
> > > Hi Rainer,
> > >
> > > On 4/17/07, Rainer Joswig <joswig at lisp.de> wrote:
> > >> I'm a bit used to the behavior of MCL when it comes
> > >> to Lisp buffers and listeners. Maybe SLIME developers
> > >> know how to achieve a similar behavior or would like
> > >> to provide something similar.
> > >>
> > >> MCL allowed multiple Lisp text editor windows and listener windows.
> > >> If there are multiple listeners one is the front most.
> > >
> > > SLIME does allow you to have multiple REPL windows. When you do "M-x
> > > slime" multiple times, it will ask you whether you want to create an
> > > additional repl.
> >
> > are you sure? i tried this today and multiple M-x slime will start
> > multiple swank-servers in the lisp but you still only get one repl
> > buffer (this looks a lot like a bug).
> Yes, I'm sure. Well, at least I'm sure it does one specific thing
> (which may not be what you think Rainer wants nor what he actually
> does want ;-) ). I don't usually use multiple repl's, so I'm not sure
> I understand the specific use case that Rainer wants to address. As I
> see it, there may be 3 different types of "new" repl's that one could
> want to have (which, depending on your specific use case may or may
> not be what is required):

The basic interaction between an Lisp editor and a Lisp listener
is a bit different in MCL. I found it a bit more convenient
then what SLIME currently does. In the simple form it
is mostly independent from the multiple buffer issue.
In my other posting I had explained the MCL interaction
a bit more.

> #1: You want to "play around" with some ideas but don't want to "muck
> up" your existing lisp environment and repl. In that case, you
> probably want to start up a new lisp instance and test things in a
> completely independent repl. When I do "M-x slime" multiple times (and
> say "n" to the "Create an additional *inferior-lisp*?" prompt), that
> is exactly what I get - multiple lisp instances with a separate repl
> for each one. I can use "C-c C-x c" to switch between them so I can do
> my "mucking around" in the one repl and do the "real stuff" in the
> other repl ("C-c C-x c" also controls which repl is "active" when
> you're in a lisp buffer compiling/evaluating/etc code).
> #2: You want to have multiple repl's on the same lisp instance (with
> each repl sharing the repl history and */**/***/etc values). This is
> useful if you want to use one repl for a demo but want to be able to
> enter other commands in another repl to set up or modify an
> environment for the demo. There are probably other use cases for this;
> however, this is what I normally use #2 for. Again (as with #1), I can
> use "C-c C-x c" to switch between the repl's so I have control over
> which one is "active". Although SLIME does not provide any standard
> function for automatically creating multiple repl's, it is easy enough
> to do if you are using a lisp with threads. In your existing SLIME
> repl, you can just enter "(swank::create-server :port some-port)" and
> then in emacs do a "M-x slime-connect" and specify the host & port. If
> you do this a lot, you could automate it with something like the
> following:
> (defun slime-new-repl ()
>   "Create additional REPL for the current Lisp connection."
>   (interactive)
>   (if (slime-current-connection)
>       (let ((port (slime-connection-port (slime-connection))))
> 	(slime-eval `(swank::create-server :port ,port))
> 	(slime-connect slime-lisp-host port))
>       (error "Not connected")))
> and just do "M-x slime-new-repl" whenever you wanted a new repl. As
> you can see from the above function, although you can specify any
> port, you can also just reuse the existing port for the separate repl,
> so it's easy enough to do when you're ssh'ing to a remote machine too.
> #3: You want to have multiple repl's on the same lisp instance (with
> each repl having it's own repl history and */**/***/etc values). I
> thought that it was possible to do this at one time with SLIME;
> however, I just had a play and I don't think there is any way that you
> can currently do this in SLIME.
> I thought Rainer was after #1 when I initially replied. If he is after
> #1 or #2, SLIME currently supports these types of multiple repl's. If
> he was looking for #3, I don't think that is currently supported.
> Maybe Rainer could indicate what specific use case he is trying to
> address with multiple repl's.

The basic use case (one Lisp editor buffer and one listener
buffer) would be:

Write and execute the code from the editor. The code
will be read from the editor using the package
of the editor (or *package* if there is none).
The execution takes place in the
context of the listener. The result is printed
in the listener. At the end of the
execution the listener prompt is updated (position
at the end of the buffer) and the *,**,***,... variables
are set/updated.

The streams of the listener will be used. Also the
printer settings of the listener will be used
for printing the result.

The forms for execution should be entered in a queue
and executed one after the other. Pressing
C-x C-e (Enter) would execute the first form. If this
form is finished, then the second form will be executed.
By default a listener has only one execution going
on at any one time.

I want C-x C-e to do something different and have it on Enter. ;-)
I never use the minibuffer for displaying Lisp results.
I'd better leave the minibuffer for command interaction
and display of messages.

SLIME (C-x C-e) currently:

SLIME does not print the result of C-x C-e in the
Listener. The result is printed in the mini-buffer.

SLIME does not set *,**,*** and related.

SLIME does interfer with its listener prompt in interactions
in the listener. If a program prints to the listener
or reads from it, the prompt is always moved to the end
while doing output.

SLIME (+ OpenMCL) happily executes two forms from
the editor via C-x C-e. But it starts the execution
of the second form immediately.

> --
> Bill Clementson


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