Long Outputs Inside Emacs Cider Repl Buffers - emacs

When using Emacs with the Cider plug-in, moving inside the REPL buffer gets incredibly slow, when there was accidently printed a huge amount of output to the REPL buffer.
Is there a way to configure Leiningen (or nrepl?) to limit the number
of lines that are allowed to be printed by one evaluation in the
repl?
Is there maybe a way to let Emacs clear the buffer after the output
happened?
Thanks in advance!

Have you tried setting *print-length*?
See this documentation and search for 'Limiting output in the REPL'.

Related

How do you cope with emacs halting on receiving big input?

I am developing project in clojure using emacs cider under windows. And sometimes I have a problem that after accidently forgotten println function or on printing contents of big file Emacs stops responding (cursor and all key combinations doesn't work) and retire into oneself for processing that information to show it in repl. The only way to continue I know is to close program and open project files from scratch. And it is so simple to get in this trap.
Are there any other better solutions or configuration restrictions?
Though this suggestion will not solve your problem completely, it can help you a little.
First, set *print-length* to some value to limit the number of items of each collection to be printed.
(set! *print-length* 10)
And use cider-connect instead of cider-jack-in. You should run lein repl in a separate console window, then run cider-connect to connect to the repl. Then you can evaluate some expressions in the console window.
It would be good if there's an option to limit the contents to be printed by number of characters, however, I couldn't find it.

How to stop evaluation of a large repl result causing slime with swank clojure to slow down?

Whenever I evaluate a large value that prints a large datastructure into the repl, slime becomes very slow from then on. Typing anything subsequently into the repl shows a delay in values appearing in the repl and further evaluation of any clojure code is slow. The only thing that seems to work is restarting the repl which doesn't seem like a solution.
An simple example of a large datastructure is slurping a file and then printing it (this could even be a fairly small file).
This seems to happen both in Win7 and Ubuntu.
Any ideas on how to stop this and why it is happening would be appreciated!
When I've run into this issue (which happens often), I simply clear the repl buffer. You can do this with C-c M-o, or by using "Clear Buffer" under the "REPL" menu item. This doesn't restart the repl, and command history and the like are unaffected.
One way you can control how much info is printed from the REPL is from clojure itself using the *print-length* and *print-level* variables.

My slime-repl is not working in ClojureBox

I installed ClojureBox and the REPL is not working.
If I type (+ 1 2) into the *slime-repl clojure* buffer and press enter, the expression text becomes bold as if it has been evaluated, but there is no result of the evaluation printed on the screen.
Can anyone help me figure out why my REPL is not printing the evaluation results?
Thanks.
Try looking in *inferior-lisp* and failing that all other buffers.
The binding of clojure's *out* plus emacs slime-swank based capture and redirection of output streams can occasionally make it seem like emacs is swallowing output. (This can get really confusing when output comes from multiple threads - definitely one of the few warts of developing clojure with the slime-swank environment.)
Have you ever tried emacs before using clojurebox? Any left behind .emacs configuration or library paths etc. can interact badly with clojurebox which, in my experience, assumes it is the only installation of emacs going onto a clean system.

Stopping infinite loops while running clojure tests in emacs with leiningen and swank/slime

In certain kinds of code it's relatively easy to cause an infinite loop without blowing the stack. When testing code of this nature using clojure-test, is there a way to abort the current running tests without restarting the swank server?
Currently my workflow has involved
$ lein swank
Connect to swank with emacs using slime-connect, and switch to the the tests, execute with C-c C-,, tests run until infinite loop, then just return but one cpu is still churning away on the test. The only way to stop this I have found is to restart lein swank, but it seems like this would be a relatively common problem? Anyone have a better solution?
Yes, it is a common problem for programmers to write infinite loops in development :). And the answer is very simple. It's called "Interrupt Command" and it is C-c C-b
Leiningen has nothing to do with this. This is SLIME/Swank/Clojure. When you evaluate code in Emacs you are spawning a new thread within Clojure. SLIME keeps reference to those threads and shows you how many are running in the Emacs modeline. If you're in a graphical environment you can click the modeline where it indicates your namespace and see lots of options. One option is "Interrupt Command"
Eval (while true) and C-c C-b to get a dialog showing a java.lang.ThreadDeath error with probably just one option. You can type 0 or q to quit that thread, kill that error message buffer and return focus to your previous buffer.
As per this old discussion, adding (use 'clojure.contrib.repl-utils)) and (add-break-thread!) to user.clj should enable you to press C-c C-c for passing SIGINT to the long running evaluation/processe.
if all else fails.. alt-x slime-quit-lisp and restart the REPL. try Psyllo's answer first of course.

How do I encourage emacs to follow the compilation buffer

Occasionally when I'm compiling, I have to scroll up my compilation buffer to see the details of an error. At this point, emacs stops "following" my compilation buffer, i.e., scrolling to automatically display new output.
I'm using Aqumacs on OS X. Any idea how I can "reattach" or re encourage the compilation buffer to follow again?
Regards,
Chris
Put in your ~/.emacs file
;; Compilation output
(setq compilation-scroll-output t)
or even
(setq compilation-scroll-output 'first-error)
to make it scroll to the first error.
Try using M-x auto-revert-tail-mode or M-x auto-revert-mode. Taken from official documentation:
One use of Auto-Revert mode is to
“tail” a file such as a system log, so
that changes made to that file by
other programs are continuously
displayed. To do this, just move the
point to the end of the buffer, and it
will stay there as the file contents
change. However, if you are sure that
the file will only change by growing
at the end, use Auto-Revert Tail mode
instead (auto-revert-tail-mode). It is
more efficient for this. Auto-Revert
Tail mode works also for remote files.
So, as Chmouel already noted, just moving point to end of buffer will also work.
I am not sure about aquamacs but for me (Emacs 23/Debian) I just go in the compilation window and place my cursor at the end of the window which will attach and follow (you can go to another window and it will still follow).