Questions tagged [functions]

use this tag for Elisp `functions` for their usage, definitions, re-definitions, defining aliases, and other standard features of function execution fundamental to Lisp programming languages. Add additional Elisp tags when the functions are about specific Emacs features.

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120 views

Symbol’s function definition is void

I am trying to make an interactive toggle in emacs 27.0.90 When I eval-region no warnings or errors are shown. However, when I do (helm/toggle-frame) in ielm it throws Symbol’s function definition is ...
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1answer
64 views

How to call a function that is the value of a variable?

Can someone explain to me why the code below throws an error (void-function fn)? (let ((lexical-binding t) (fn (lambda (y) (+ y 4))) (x 4)) (pcase x (10 (- x 2)) (4 (fn x)))) ...
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3answers
1k views

Is everything in Emacs made of functions?

Being more used to Vim, I know that it was correct to think "everything in Vim is a macro" but what about Emacs? Is it fine/correct to think that everything is a function in Emacs?
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1answer
54 views

Inconsistent behavior when calling #'funcall with a macro

I would have thought that both of the funcall's the follow would have yielded the same result, but they don't and I'm trying to understand why. (defmacro test/z () "z") (funcall (function test/z)) ;;...
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3answers
42 views

How to find information about a function?

To be able to learn about functions on my own I would like to know where I can find information about them (within emacs or otherwise).
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1answer
39 views

Why can't I directly invoke the result of apply-partially?

I'm confused about return value of apply-partially. Documentation states that it returns a function, and source of the function shows that it actually retruns a lambda. But I can't invoke the return ...
0
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1answer
30 views

Convert function-quoted form #'… to string

I have tried (symbol-name x), but it doesn't work if the argument is a lambda: ok: #'execute-extended-command not ok: #'(lambda (&optional frame) (interactive) (message "hi 8"))
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1answer
36 views

general function to concat token at point with function and send to *R*

I'm moving my R setup over to emacs and ess -- and am struggling with the emacs / LISP customisation process. In an answer to another question, I learnt how to create a function that concats a ...
1
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1answer
20 views

Wrong type argument: symbolp, 10

I would like create function that ask me how length I want the Pomodoro but it say wrong type argument. (defun changePomoLength () (interactive) (set-variable org-pomodoro-length (read-string "...
2
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1answer
113 views

Why is function defined by defun not bound

intro Sometimes I want to generate a function programmatically as opposed to defining one with defun. You may wondering why I'd want to do this. Well, it's complicated but just bear with me for a ...
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3answers
71 views

Default argument when nil is provided

I'm writing a function which wraps org-export-as for use in html conversion of a file. In this function, I define the options for org-export-with-toc, org-export-with-section-numbers, and org-html-...
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2answers
41 views

Why does `narrow-to-region` complain that its args are not `integer-or-marker-p`?

I have some functions that depend on smart-parens code. (defun outer-paren () "Move point to the outermost parenthesis." (interactive) (ignore-errors (while t (up-list))) (sp-...
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2answers
50 views

Add a number to every item in list

How do I add a number, say 2, to every item in a list? (setq x '(1 2)) (+ 2 x) (mapcar '2+ x) (loop for i in x do (+ 2 i)) (dolist (i x) (+ 2 i)) None of the above work.
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1answer
69 views

built-in function to return the argument itself

The line below shows the first element which is not nil. (message "%s" (cl-some #'(lambda (x) x) '(nil nil "hello" nil))) ;; Output: hello Is there a built-in function which is equivalent to (...
0
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1answer
26 views

Source C code of function 'apply'

I referenced C-h f apply for the source code of "apply", it prompts References C code is not yet loaded. but does not hint the destination file. Execute grep-find within Emacs repo thus return no ...
0
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2answers
38 views

How do I define a function to execute as a command with M-x? [duplicate]

I wish to M-x my-func and let my code run. This seems basic but where can I get more documentation about this, if possible inside emacs itself?
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1answer
31 views

Evaluate allows for combinations whose operators are compound expressions

I find the amazing power of scheme in sicp Exercise 1.4. Observe that our model of evaluation allows for combinations whose operators are compound expressions. Use this observation to describe ...
2
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1answer
86 views

How to introspect function & macro arguments in elisp?

Is there a programmatic way to access function/macro arguments, Something like this, which returns the the arg count and true if it accepts any number of additional arguments. eg: (number-of-...
0
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1answer
15 views

Usage of vhdl-mode's vhdl-compose-place-component function

The command vhdl-compose-place-component is supposed to create the text to place a component. I can't figure out how to specify which component it places, though. Right now, when I use it, it places a ...
1
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1answer
36 views

Use Elisp macro instead of two function arguments?

Is the following sort of shortcut macro possible to implement? (defmacro region-end-beg () "Replacement for '(region-end) (region-begin)' in source code" (...)) So that (buffer-substring (region-...
1
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2answers
54 views

I want to simplify repeated calls in my init.el file

I've got a lot of: (desktop-save-mode 1) (show-paren-mode 1) which I'd like to collapse into: (mapcar (lambda (fn) (fn 1)) '(desktop-save-mode show-paren-mode)) but I get an error: Symbol’s ...
0
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1answer
88 views

how to bind custom commands to keys in existing mode map?

I wrote some extra commands for Python mode: python-insert-quote and python-insert-double-quote. I want to have these commands be available in the minibuffer when python-mode is active. How can I add ...
0
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1answer
81 views

What is a better way to write this function?

(cl-defun filename-from-buffer (&key get-ext get-path) (let ((filename (buffer-name)) (pathname (buffer-file-name))) (setq ret (car (split-string filename "\\."))) (when get-path ...
0
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1answer
42 views

Force function evaluation when setting variable value? [duplicate]

I have these functions defined in my early-init.el. I'm trying to change the location of where my backups are saved and keep getting a Wrong type argument stringp (djm/emacs-cache "backups/"). early-...
0
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2answers
86 views

How to know whether a function is implemented in C or Elisp?

I want to switch some behavior in my .emacs based on whether I have the new native fast json-serialize which is implemented in C rather than Elisp. Is there a simple way to detect whether a function ...
0
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0answers
15 views

Choose to use a function between emacs packages or libs

Suposse that I want to use the function dolist from package cl (I know that is obsolete and als have cl-lib package). but when I'm looking for documentation (C-h f dolist) I get the following: ...
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1answer
133 views

How to execute one line in the .emacs file?

To test a function definition, for example : (defun count-words-buffer () (let ((count 0)) (goto-char (point-min)) (while (< (point) (point-max)) (forward-word 1) (setq count ...
0
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1answer
19 views

How to set value vc-git-grep-template within function

I have a working sexp for configuration vc-git-grep: (setq vc-git-grep-template "git --no-pager grep -n -i -e <R> -- <F>") Then in dired-mode I evaluate M-x vc-git-grep and everething ...
3
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1answer
66 views

Octal character representation in keyboard macros

I generated a macro as a help for generating indices for words I have marked before. Now this macro looks as follows (fset 'index "\367\\index{\C-y") What does \367stand for and where can I look ...
0
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1answer
47 views

Is it possible to make a function local to the buffer?

I want to override the function helm-swoop-pre-input-optimize in man mode using its hook, but not anywhere else. Is there something similar to make-local-variable for functions?
1
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0answers
42 views

execute-kbd-macro apparently not working according to its doc?

The doc of execute-kbd-macro says: (execute-kbd-macro MACRO &optional COUNT LOOPFUNC) ... If MACRO is a symbol, its function definition is used. I tried M-: (execute-kbd-macro 'ignore). ...
2
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3answers
752 views

Are local nested functions possible in elisp?

It it possible to declare functions whose names are only available in the scope of another function, similar to let? e.g.: (defun my-fn (x y) (let ((my-local-fn (lambda (a b) (message "%S" (- a b)...
1
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2answers
51 views

' versus #' what are the differences and when should I choose one over the other? [duplicate]

Both seem to work equally well when mapping a function over a list, for example. (mapcar #'1+ (list 1 2 3)) ;; => (2 3 4) (mapcar '1+ (list 1 2 3)) ;; => (2 3 4)
4
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3answers
393 views

How to bind keys to a function which can be defined per-mode?

Currently I have variables defined with setq-local, this is useful for modes, so I can define variables only for a particular mode. How can this be done for functions? I'd like to have a function, ...
1
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1answer
251 views

Disable minor modes like flycheck-mode and flymake-mode by default

I disable the following the modes in init.el ;;flycheck-mode ;;flymake-mode ...
1
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2answers
180 views

How to save all modified buffers and kill emacs

I use the well known key-binding C-x C-c to quit emacs. However this command asks y/n confirmation to save modified buffers and if there are process buffers (eg. Shell) it also asks for yes/no ...
2
votes
1answer
60 views

trying to make a self-modifying function [duplicate]

I'm trying to make a function that returns a list of perfect numbers: A perfect number is a positive integer that is equal to the sum of its proper positive divisors For instance, 28 is perfect ...
5
votes
1answer
60 views

Can a symbol have a function, variable, and class?

Q: can one symbol refer to a function, a variable, and a class? Elisp is a Lisp-2 in which a symbol can have separate function and variable values. So, for example, I can define the following ...
1
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1answer
47 views

How to create a function with a computed name?

Let's suppose I have a string "foo" and want to create a function that would be an equivalent of (defun foo (...) ...). Is there a nice way to do it? I played with make-symbol and fset, but could ...
8
votes
2answers
879 views

How to delete a function?

For what I do I tend to define a lot of functions that I use temporarily. Life span is usually about 1-2 weeks - and then I define a new set of functions. I was not able to find where these ...
4
votes
2answers
544 views

defun in defun is not local?

I am reading SICP to learn Lisp, the book uses Scheme dialect. I want accommodate it to emacs lisp, I find something weird in 3.1.1 and cannot figure it out, say I have a test.el file: (defun make-...
0
votes
1answer
49 views

How can I get git-gutter:next-hunk to NOT loop around at buffer bottom?

As per the title, I would like to stop processing at the end of a buffer and not loop around to the top. I find it easier to keep track of what I am doing that way. TIA.
1
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1answer
76 views

Problem with file-exists-p function on Linux running as VirtualBox guest

Until this morning, my emacs setup (running on Arch Linux as a VirtualBox guest) was working absolutely fine. Then for no obvious reason I started experiencing the following issue: If I opened an ...
13
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1answer
1k views

Why can't I bind my function to a key or call it with M-x?

I wrote a function, and I want to call it via M-x, and bind it to a key. This is my function: (defun my-function () (message "This is a great function")) If I try to call it with M-x my-function,...
0
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1answer
47 views

Apply of a logic function over a list

I'm trying to apply a logic function over a list, but: e.g.(apply 'and some_list) give me Invalid function: and. There is a way to apply a logical function to a list?
2
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2answers
108 views

Does `car` on an non-lazy function generated list evals the whole list?

I want to get in a huge directory the first file which satisfies some condition, something like (require 'seq) (require 'f) (defun lazy-filter-file (pred path) (car (seq-filter pred (f--files path ...
2
votes
2answers
157 views

Elisp - Activate and Deactivate Linum-Mode when Goto-Line is Triggered

I switched to Emacs from Vim and because of Vims functionality of giving keys a prefix, (for example to jump up several lines etc.) i installed relative-linum-mode right away. Now i found out about ...
1
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1answer
33 views

Calling locally defined function via function parameter

Interface, by example: (my-run-command '(my-append (3 6 8) (4 5))) Desired output: (3 6 8 4 5) Implementation, with bits missing: (defun my-run-command (command) (let ((my-append 'append)) [...
0
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1answer
94 views

use a function to get file in compilation-error-regexp-alist

I have used compilation-error-regexp-alist a lot so I am familiar with the syntax. However for this particular error I need to use a function to get the file because I need wildcards. Here is the ...
3
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1answer
77 views

How to get Emacs to know that a symbol has a function definition

While reading the source file prelude-ivy.el in the Prelude modules directory, I saw that there was a warning associated with "here" in the last line, specifically that prelude-required-packages was ...