I use paredit on emacs with SLIME's repl. This means that at any point during my typing on the repl, my s-expressions are balanced.
However, they may not be complete, and I might want to continue typing inside them in another line, as follows:
CL-USER> (defun print-hello ()
)
When I start a new line by pressing the enter key, however, the SLIME repl executes my incomplete expression. I want it to wait for me to complete the expression, as follows:
CL-USER> (defun print-hello ()
(format t "Hello, world"))
How do I make this happen please?
For that situations, when writing long s-expressions in REPL I think that the best way is to use the slime scratch buffer. you can edit it and after that execute with
C-j
No problem pressing enter inside the buffer, I'm using sly but the capture could be like this:
(defun print-hello ()
(format t "Hello, world"))
; => PRINT-HELLO
Also another alternative is working without the last parent :-(
or as suggested in a comment by #jkiisky, type the expression and add in the middle of the s expression C-j
CL-USER> (defun
)
Related to your question, lispy provides integration with SLIME.
I typically never type anything into the REPL buffer. Instead, I edit all code in place in the source file, and use e to eval the current sexp.
lispy is also a super-set of paredit, if compatibility is your concern.
Related
I'm on ubuntu 19.
Using emacs, slime and sbcl to practice some lisp.
Currently I have one buffer in slime mode in one window and the slime-description in the other window.
When I want to execute a line, I write it on the buffer and press C-c C-p.
But when I try to do the same for the line
(defvar *name* (read))
to set the the name var with the user input, nothing is happening.
Why ?
Also I would like to execute the whole script and not one line at a time, how do I do that ?
'Nothing is happening' because read is waiting for you to type something at the REPL. If you look at the REPL you will be confused because the form you are evaluating is not displayed, so all you see is ... nothing, but you need to type something at it. Further, it's not clear from your description what buffers you have displayed, but I suspect the REPL is not one of them, which is going to make things even worse.
I don't know how other people use SLIME, but what I do is to have at least the REPL (the thing you get after typing M-x-slime in one window, and a file I am working on in another. You can then interact with the REPL just by typing at it, and send code to the running lisp from the file with C-M-x or any of the other commands (in particular things like C-c C-k which compiles & loads the file.
However you almost never want a file you are compiling or loading to include anything which causes read to be called at compilation or load time: the results are going to be mysterious to put it mildly: the system will just stop with no prompt waiting for you to type something. It makes much more sense to do that in the REPL:
CL-USER> (defvar *name* (read))
(here is the data I am typing in)
*NAME*
Indeed, even when you go to some lengths to make calls to read non-mysterious in files being loaded, you have to go to yet further lengths to make them safe. Consider this file, toxin.lisp:
(defvar *my-thing*
(progn
(format *query-io* "~&thing? ")
(finish-output *query-io*)
(read *query-io*)))
Now:
$ lisp
[...]
(load "toxin" :verbose t)
;Loading #P"toxin"...
thing? #.(quit)
Of course there are much worse things I could have said than that to the Lisp.
I'm starting to play with CLisp, and therefore Emacs too, including the "SLIME" plugin (or whatever it's called. How is it called?)
So I've been playing with the REPL for quite some time now, and defined a lot of functions in there with (defun).
Unfortunately, none of these functions have been written in a text file, and I don't fancy retyping all that. Is there a way I could dump or otherwise save the work that has been done in the REPL to a file? (bonus points if the file is Lisp source code :) )
SLIME is an elisp program for interacting with Lisp.
There's no simple option to recover functions you've typed only into the repl into a file. function-lambda-expression can sometimes return code, but it often does not.
If the repl is still in a buffer, you could copy the whole thing into a file and then use string or regexp replacement to isolate the function definitions.
It's not too hard to avoid this problem in the future.
Most people work by writing definitions into a file, and then using a key combination to send them to Lisp, bypassing the REPL. I use the C-c C-c combination when the cursor is on a function to compile and load the expression. C-x C-e also works. Then I switch the the REPL to actually use the function.
See also the function DRIBBLE, which makes sure a log is written.
foo:~$ clisp
...
[1]> (dribble "foo.text")
#<OUTPUT BUFFERED FILE-STREAM CHARACTER #P"foo.text">
[2]> (+ 3 4)
7
[3]> (defun bar (baz) (* baz baz))
BAR
[4]> (bar 10)
100
[5]> (quit)
Bye.
Let's look at the file:
foo:~$ more foo.text
;; Dribble of #<IO TERMINAL-STREAM> started on 2015-05-08 21:38:48.
#<OUTPUT BUFFERED FILE-STREAM CHARACTER #P"foo.text">
[2]> (+ 3 4)
7
[3]> (defun bar (baz) (* baz baz))
BAR
[4]> (bar 10)
100
[5]> (quit)
Bye.
The last paragraph in Xach's answer is what it is all about.
When programming in Lisp, typing function definitions directly into the REPL is the wrong way to do it. The right way is to set up your text editor (emacs) so that with certain keystrokes, the expression at the cursor (the entire function definition) is sent to the REPL. Then to invoke a function, you switch to the REPL. This is what SLIME is for.
Strictly speaking, the text in your emacs buffer doesn't have to be written to a disk file, in which case it will be gone after you close the editor. But normally you save it to a file.
You can search through your REPL history for the function definitions. If you have the beginning of an expression already typed in, then SLIME will only cycle through previous entries that begin with the same thing:
CL-USER> (defun
Press M-P from there, and you'll cycle through all the defuns you've typed in.
I am an hour new into programming in Emacs lisp. I have a little experience with scheme so I understand the big picture of lisps in general. However, I have only used the "pure functional" subset of scheme and do not know how to do practical tasks.
Write now, I know that C-x C-e will evaluate the code enclosed by the parentheses' by the current cursor position.
I wish to loop from i = 1 to 10 and print the values of i out. How is this done? I tried the following:
(defvar i 1)
(while (< i 11)
(print "i: " i)
(setq i (+ i 1)))
Emacs tells me: invalid function 0.
How do I do this correctly?
Why is emacs telling me invalid function 0
Feel free to give me tips about how to use the scratch buffer (all I know is C-x C-e evaluates) in emacs. Thanks for all the help!
EDIT1: Could someone tell me how to print out sequential values of i using a while loop?
EDIT2: When I evaluate the code, it opens up another tiny buffer showing each value of i one at a time. However, it is not a large buffer and only shows values of i from 13 to 19. When I try to get into that buffer, it closes immediately. How do I "scroll" through that tiny buffer? Note that I use emacs 24.3 through the terminal
EDIT3: I figured out that the tiny buffer is the Messages buffer. Is there a better way to view the output of my elisp code? The Messages buffer is full of other junk from evaluating things in emacs.
First and foremost, enable "Enter debugger on error" from the Options menu now and add (setq debug-on-error t) or (custom-set-variables '(debug-on-error t)) to your ~/.emacs.el.
Then you will get a *Backtrace* buffer on C-x C-e:
Debugger entered--Lisp error: (invalid-function 1)
1(10)
print("i: " 1)
(while (< i 11) (print "i: " i) (setq i (+ i 1)))
eval((while (< i 11) (print "i: " i) (setq i (+ i 1))) nil)
eval-last-sexp-1(nil)
eval-last-sexp(nil)
call-interactively(eval-last-sexp nil nil)
command-execute(eval-last-sexp)
which shows that the error comes from print.
C-h f print RET will tell you why, but the upshot is that you want to use insert instead of print here.
Just as an added note, since you mentioned knowing some scheme -- if you like the interactive REPL that you can use in typical scheme environment, you might like ielm -- I think it probably stands for Interactive Emacs Lisp mode. Not sure. Anyway, M-x ielm RET will open up an emacs lisp REPL. Sometimes it is actually useful -- for example, when you want to inspect the content of a variable with a lot of data in it, ielm will print the whole thing out. Ielm is built in to my Emacs. Not sure when it was added to the standard distribution, but the earliest copyright in the source says 1994, so it is probably in your Emacs.
You can evaluate Emacs-Lisp sexps in *scratch* or in any other buffer in the same mode or (my preference) in mode emacs-lisp-mode.
In *scratch* you need only hit C-j (newline) after a sexp to evaluate it. In an emacs-lisp-mode buffer you can, as you said, use C-x C-e after a sexp. Or you can use M-x evaluate-region after selecting one or more sexps. As always, C-h m in any mode tells you about it, and usually lists important key bindings.
You can also check a global variable value using C-h v SOME-VAR. And you can evaluate any sexp on the fly from the minibuffer, using M-:. For example: M-: (setq foo (+ 42 (length bar)))
Wrt the debugger:
As #sds mentioned, debug-on-error puts you in the debugger when an error is raised. You can also set debug-on-quit and then enter the debugger using C-g to quit (e.g., during a loop).
If you know the function you want to debug, you can use M-x debug-on-entry.
Step through the debugger using d, or skip to the end of a step using c. Use q to quit the debugger.
You can also insert calls to function debug in source code, as debugger entry points: (debug).
The backtrace in the debugger is always more informative if you load the relevant source file e.g., foo.el, instead of the byte-compiled file, e.g., foo.elc. So before you use M-x debug-on-entry use C-h f to find out which file the function is defined in, and then load that file using M-x load-file /path/to/the/file.el.
There is also another debugger, besides debug -- look for edebug in the Elisp manual. Some people prefer edebug; I prefer debug.
I was just typing in this sort of code for Nth time:
menu.add_item(spamspamspam, "spamspamspam");
And I'm wondering if there's a faster way to do it.
I'd like a behavior similar to yasnippet's mirrors, except
I don't want to create a snippet: the argument order varies from
project to project and from language to language.
The only thing that's constant is the variable name that needs to be
repeated several times on the same line.
I'd like to type in
menu.add_item($,"")
and with the point between the quotes, call the shortcut and start typing,
and finally exit with C-e.
This seems advantageous to me, since there's zero extra cursor movement.
I have an idea of how to do this, but I'm wondering if it's already done,
or if something better/faster can be done.
UPD The yasnippet way after all.
Thanks to thisirs for the answer. This is indeed the yasnippet code I had initially in mind:
(defun yas-one-line ()
(interactive)
(insert "$")
(let ((snippet
(replace-regexp-in-string
"\\$" "$1"
(substring-no-properties
(delete-and-extract-region
(line-beginning-position)
(line-end-position))))))
(yas/expand-snippet snippet)))
But I'm still hoping to see something better/faster.
yasnippet can actually be used to create a snippet on-the-fly:
(defun yas-one-line ()
(interactive)
(let ((snippet (delete-and-extract-region
(line-beginning-position)
(line-end-position))))
(yas-expand-snippet snippet)))
Now just type:
menu.add_item($1,"$1")
and call yas-one-line. The above snippet is expanded by yasnippet!
You could try
(defvar sm-push-id-last nil)
(defun sm-push-id ()
(interactive)
(if (not sm-push-id-last)
(setq sm-push-id-last (point))
(text-clone-create sm-push-id-last sm-push-id-last
t "\\(?:\\sw\\|\\s_\\)*")
(setq sm-push-id-last nil)))
after which you can do M-x sm-push-id RET , SPC M-x sm-push-id RET toto and that will insert toto, toto. Obviously, this would make more sense if you bind sm-push-id to a convenient key-combo. Also this only works to insert a duplicate pair of identifiers. If you need to insert something else, you'll have to adjust the regexp. Using too lax a regexp means that the clones will tend to overgrow their intended use, so they may become annoying (e.g. you type foo") and not only foo but also ") gets mirrored on the previous copy).
Record a macro. Hit F3 (or possibly C-x (, it depends) to begin recording. Type whatever you want and run whatever commands you need, then hit F4 (or C-x )) to finish. Then hit F4 again the next time you want to run the macro. See chapter 17 of the Emacs manual for more information (C-h i opens the info browser, the Emacs manual is right at the top of the list).
So, for example, you could type the beginning of the line:
menu.add_item(spamspamspam
Then, with point at the end of that line, record this macro:
F3 C-SPC C-left M-w C-e , SPC " C-y " ) ; RET F4
This copies the last word on the line and pastes it back in, but inside of the quotes.
As an Emacs beginner, I am working on writing a minor mode. My current (naive) method of programming elisp consists of making a change, closing out Emacs, restarting Emacs, and observing the change. How can I streamline this process? Is there a command to refresh everything?
You might try using M-C-x (eval-defun), which will re-evaluate the top-level form around point. Unlike M-x eval-buffer or C-x C-e (exal-last-sexp), this will reset variables declared with defvar and defcustom to their initial values, which might be what's tripping you up.
Also try out C-u C-M-x which evaluates the definition at point and sets a breakpoint there, so you get dropped into the debugger when you hit that function.
M-x ielm is also very useful as a more feature-rich Lisp REPL when developing Emacs code.
M-x eval-buffer should do it.
What Sean said. In addition, I have (eval-defun) bound to a key, along with a test. The development loop then becomes: 1) edit function, 2) press eval-and-test key, 3) observe results, 4) repeat. This is extremely fast.
During development I write a test, bind it to jmc-test, then use the above key to run it on my just-edited function. I edit more, then press key again, testing it again. When the function works, I zap jmc-test, edit another function, and write another jmc-test function. They're nearly always one line of code, so easy to just bang out.
(defun jmc-eval-and-test ()
(interactive)
(eval-defun nil)
(jmc-test))
(define-key emacs-lisp-mode-map (kbd "<kp-enter>") 'jmc-eval-and-test)
(when t
(defun myfunc (beer yum)
(+ beer yum))
(defun jmc-test () (message "out: %s" (myfunc 1 2))))
When editing "myfunc", if I hit keypad enter, it prints "out: 3".
It all depends on what you're writing and how you've written it. Toggling the mode should get you the new behavior. If you're using [define-minor-mode][1], you can add code in the body of the macro that keys off the mode variable:
(define-minor-mode my-minor-mode
"doc string"
nil
""
nil
(if my-minor-mode
(progn
;; do something when minor mode is on
)
;; do something when minor mode is off
)
But, another way to check it quickly would be to spawn a new Emacs from your existing one:
M-x shell-command emacs&
I just define a function called ldf (short for load-file) in my .emacs file,
like this:
(defun ldf (arg) (interactive "P") (load-file (buffer-file-name)))
As you can see, this little function looks up the filename of the current buffer and then loads the file. Whenever I need to reload the current buffer elisp file, just type "M-x ldf"