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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3
votes
1answer
117 views

is there a function that can partially apply arguments on a function with order?

apply-partially cannot specify the order. Is there one from the default Emacs installation that can specify order?
0
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3answers
49 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-...
1
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2answers
35 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
53 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
votes
1answer
111 views

function that takes a function as argument and returns a new function

I'd like to write an elisp-function that has a function as argument and returns a new function. Let's say the new function double-the-function should write the returned value of the argument-function ...
4
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2answers
164 views

Calling a function with a shorter but unknown argument signature length

Is there a terse idiomatic way of calling a function in the manner of funcall (dereferencing function symbols) when that function may have a variably shorter function signature? Say for example: a ...
-1
votes
2answers
47 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.
1
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1answer
67 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
22 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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1answer
12 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 ...
0
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2answers
28 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?
0
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1answer
30 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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2answers
1k views

Symbol's function definition is void: insert-string

;; Specify the startup banner. Default value is `official', it displays ;; the official spacemacs logo. An integer value is the index of text ;; banner, `random' chooses a random text banner in `core/...
0
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1answer
146 views

Custom search function for dictionary lookup

I have a plain text dictionary in which each headword is matched by ^# \(† \)?headword, How can I make a custom search function that relieves me of typing the whole regex every time I want to look ...
2
votes
1answer
65 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
votes
1answer
37 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-...
1
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1answer
35 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-...
2
votes
7answers
792 views

How to get the function help without typing?

I'm already used to press C-h f and type a function name to ask for help on that function. But if the function name is already under the cursor (e.g. while visiting the .emacs configuration file), is ...
0
votes
1answer
53 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
votes
1answer
64 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
votes
2answers
67 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 ...
3
votes
3answers
563 views

Org-mode link to function definition

Is it possible to link to a function definition in a source code file, rather than a fixed line number?
0
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0answers
14 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: ...
3
votes
3answers
354 views

Trace calls to a function with the parameters

I need to track the calls to org-tags-view to discover the params passed to it. I tried an advice: (defun his-tracing-function (orig-fun &rest args) (message "org-tags-view called with args %S" ...
1
vote
1answer
89 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
votes
1answer
17 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
votes
1answer
55 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
votes
1answer
45 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
vote
0answers
37 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
votes
3answers
509 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
vote
2answers
43 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)
9
votes
2answers
569 views

When should sharp quotes be used?

I see sharp quotes being used in other people's eLisp code, and I use them myself, but I'm not completely clear on when they are appropriate and when not. Could anyone clarify on exactly when it's ...
4
votes
3answers
330 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
vote
2answers
141 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 ...
1
vote
1answer
206 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 ...
2
votes
1answer
56 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
54 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
vote
1answer
45 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 ...
30
votes
4answers
3k views

When to sharp-quote a lambda expression?

Q: When, if ever, is it useful to sharp-quote a lambda, and when, if ever, must we not sharp-quote a lambda? People use lambdas in three ways: plain: (lambda (x) x) quoted: '(lambda (x) x) sharp-...
5
votes
1answer
666 views

What is identity doing? [closed]

I've seen this sort of thing a few times: (mapconcat 'identity '("" "home" "alex " "elisp" "erc") "/") => "/home/alex /elisp/erc" which means mapconcatwants a function in the second position, ...
2
votes
2answers
168 views

Why use `defsubst` in `man.el`?

I recently noticed an issue in man.el, in which sections in Man--sections are listed backwards. That is, the value is is something like: (#("SEE ALSO" 0 8 (face Man-overstrike)) #("COPYRIGHT" 0 9 ...
4
votes
2answers
106 views

Understanding “It is bound to …” message in describe-function

If you ask for a function description, there is a line that starts: It is bound to <...> <...> <...> For example, for isearch it says: It is bound to <menu-bar> <search&...
7
votes
2answers
812 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
474 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-...
1
vote
1answer
70 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 ...
0
votes
1answer
46 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.
13
votes
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
votes
1answer
43 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
votes
2answers
107 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
135 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 ...