Questions tagged [elisp]

for questions about Emacs Lisp as a Lisp dialect, that is, questions *about the language* itself. DO NOT USE it for questions about customization or how to write an application. Emacs Lisp is the scripting and programming language that the Emacs editor is built on.

Filter by
Sorted by
Tagged with
0
votes
4answers
102 views

How to delete surrounding brackets?

I'd like to be able delete the innermost brackets around the current point. What's a good way to do this? While the evil-surround package can do this, it needs to take a bracket type as input, so ...
2
votes
1answer
51 views

Difference between pcase-let & cl-destructuring-bind?

I noticed both pcase-let and cl-destructuring-bind seem to perform the same operation. Is there any difference or reason to use one instead of the other? eg: (pcase-let ((`(,filename ,buf) (pop ...
3
votes
1answer
40 views

Why does `make-symbol` work in macro expansion, just as `gensym` works?

In the dash library I noticed the use of make-symbol to avoid symbol conflicts during macro expansion. (defmacro --filter (form list) "Anaphoric form of `-filter'. See also: `--remove'." (declare ...
0
votes
2answers
62 views

What is #'eq and how does it differ from 'eq [duplicate]

I've seen a few snippets of code where symbols were prepended by #' instead '. like the following snippet (seq-count #'not (seq-mapn #'eq seq1 seq2)) What is the difference and why couldn't I just ...
1
vote
1answer
61 views

“Symbol's value as variable is void: *” using load-file

I have this function in my config file and for some reason, I'm getting this error: Symbol's value as variable is void: *. (defun reload-config() "Reload config.org" (interactive) (load-...
2
votes
1answer
49 views

Why do I get free variable warnings with use-package?

I have, for instance, this in my .emacs: (use-package company :bind (("M-RET" . company-complete)) :demand ; load it now (better for eglot) :config (global-...
2
votes
3answers
393 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
0answers
34 views

Has elisp some object inspector? [closed]

Do you know about some elisp object inspector? I want object tree view similar to ones in javascript consoles in browsers. Object: (list (list "foo" "bar" "baz") "some" "thing") Inspector: list | ...
1
vote
2answers
41 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)
2
votes
1answer
83 views

Is there a timsort implementation in Emacs Lisp?

Timsort is the default sort algo of Python and Java and it performs better than mergesort on roughly sorted lists. I could not find any implementation of this in Elisp. How can I find out whether ...
1
vote
1answer
72 views

Updating code from lexical-let to lexical-binding: t

This code shows an elisp function (third example) using lexical-let, which is now passe as I understand. How would it be written today with lexical scope now being a quasi-built-in feature of elisp? ...
2
votes
1answer
137 views

How to write a list literal with conditional items? [duplicate]

Given a list literal '(1 2 3) is it possible to conditionally include parts of the list? eg: '(1 2 3 (when thing-is-true '(10 11 12))) 4 5 6) Which would result in '(1 2 3 4 5 6) or '(1 2 3 ...
42
votes
9answers
6k views

How can I start learning Emacs Lisp?

Background: I'm mostly a vi user and am converting to Emacs. Past the basics and now use it for writing code in C and some Python with plans to do an R conversion too. I wrote (Common) LISP for ...
3
votes
1answer
116 views

About closure creation

After reading this article about readable closures, I check that: Since closures are byte-code function objects, they print readably. You can capture an environment in a closure, serialize it, ...
2
votes
2answers
132 views

Evaluating symbol in function arguments affected by destructive operations?

While evaluating a function call, the arguments is from left to right. For example, (let ((x '(1 2 3))) (list (nreverse x) x)) ;; => ((3 2 1) (1)) The first argument (nreverse x) evaluates to (...
1
vote
1answer
100 views

are braces `{` and `}` used at all in elisp?

What is the convention for using { and } characters in Emacs Lisp if they are used at all? Do macros make use of them?
3
votes
1answer
64 views

formatting of elisp file is different in emacs and other text editor

I'm having an issue with formatting in that when I'm in emacs, the formatting looks fine: but when the file is viewed with a different text editor, the spaces are different. this only occurs in the ...
1
vote
1answer
62 views

oddp vs cl-oddp in elisp script

I am trying to write a short script file with elisp for the first time which will serve me to install all the required packages that I use. Thus when I change from one computer to another, I can get ...
1
vote
1answer
82 views

\\{ in a doc string: what does it mean/do?

What does this backslash syntax mean? (defun elfeed-search-mode () "Major mode for listing elfeed feed entries. \\{elfeed-search-mode-map}" (interactive)
1
vote
1answer
117 views

Return Value of apply-partially

I'm playing around with apply-partially and I'm confused about what gets returned when calling this function. The documentation states that apply-partially returns a function, but then I'd expect to ...
10
votes
3answers
189 views

Why does defvar scoping work differently without an initvalue?

Suppose I have a file named elisp-defvar-test.el containing: ;;; elisp-defvar-test.el --- -*- lexical-binding: t -*- (defvar my-dynamic-var) (defun f1 (x) "Should return X." (let ((my-dynamic-...
1
vote
1answer
278 views

What paradigm shift of my thinking must happen to understand the essence of Emacs/Emacs Lisp? [closed]

I've always had "AHA!"-moments when encountering new concepts or ideas in programming. That's when things start clicking for me. And I think I haven't yet had that moment with Emacs/Emacs Lisp yet. ...
1
vote
1answer
108 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?
4
votes
2answers
105 views

How can I define new places for setf?

Q: how do I teach setf about new places it can set? In common lisp, one uses the macro defsetf to tell setf about new places it can set. In elisp, that macro exists in in the cl library, but, as far ...
4
votes
1answer
509 views

Call a function and insert text in minibuffer prompt

I'd like to define a key binding that calls a function and inserts some default input in the function's minibuffer prompt. For example, I'd like to call the command ivy-switch-buffer and automatically ...
9
votes
2answers
508 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
0answers
185 views

Is there an ELISP decompiler?

I'm thinking of writing one so that when I get those horrible tracebacks from bytecode files, I can better see where I was at. Is there one already? Are there any other tools for showing an error ...
5
votes
3answers
543 views

Is there an equivalent for defparameter on emacs-lisp?

I know we have defvar and setq. defvar has a special meaning on defining global variables because the assignment only happens once. So I was thinking about use setq to get the desired behavior of ...
6
votes
3answers
3k views

How to wrap a single string literal across multiple lines?

Is it possible to write a single line for an Elisp string: "hello world" As: "hello world" Without inserting a newline character? (wrapping a string literal). I read that adding a tilde at the ...
2
votes
1answer
314 views

How to use custom macro indentation in elisp?

This blog post shows that its possible to indent like this: (lispy-dotimes arg (when (= (point) (point-max)) (error "Reached end of buffer")) (forward-list)) Instead of this: (lispy-dotimes ...
2
votes
1answer
411 views

orgmode - babel language elisp vs. emacs-lisp

I am not sure what's the difference between elisp and emacs-lisp. In my environment, both work for elisp code but I did not found elisp from the load language list: #+BEGIN_SRC elisp :results output (...
1
vote
1answer
64 views

practical relevance of storing value and function into one symbol

With Emacs Lisp it is possible to store a value and a function within the same symbol. (setq foo 6) (defun foo () (message "blah %d" foo))) Then you can do: (symbol-function 'foo) which returns the ...
1
vote
1answer
89 views

How to print a quoted sexp using '… (reader syntax) instead of using (quote …)?

The result of (print 'foo) is (quote foo). Is there a similar function whose result is 'foo, which is what people generally write?
5
votes
1answer
143 views

Elisp backtrace print garbage messages

I'm using emacs 25.2 on osx 10.12 and following elisp intro to produce some error message intentionally. (This is a list) After I run C-x C-e on this line. A backtrace buffer appeared as supposed ...
1
vote
0answers
34 views

How to de-instrument elisp function? [duplicate]

To instrument an elisp function means to set up Emacs in such a way that whenever the function gets executed, debug mode is entered so the function can be executed stepwise. To instrument a function, ...
0
votes
0answers
59 views

Byte Compiling Functions Using `defalias` for `progn`

The following code: (defalias 'new-progn 'progn) (defun foo () (new-progn "foo")) (byte-compile 'foo) (foo) gives this error: Debugger entered--Lisp error: (invalid-function #<subr progn>) ...
5
votes
0answers
142 views

Structure-preserving copying of sequences

The form (cl-copy-tree TREE t) returns a deep-copy of a sequence TREE. The the Common Lisp Hyper Spec explains that copy-tree does not preserve circularities and sharing of substructures. I.e., even ...
1
vote
2answers
187 views

Wrapper objects / types for Emacs Lisp primitives?

I'm curious if there's any precedent for wrapper objects or types in Emacs Lisp. Javascript notably has built-in types that wrap built-in literal types and those objects can largely be used in the ...
1
vote
1answer
55 views

File mode name with -mode suffix or not?

I am not sure when I should name file x-mode.el and when x.el. Note that because of established practice mode writer should put (provide 'x) or (provide x-mode) to the end of file and end-users load ...
7
votes
2answers
475 views

The default value of buffer-local variable not set until first `setq`

Say I define a buffer-local variable foo, and its default value is "a": (defvar foo "a") (make-variable-buffer-local 'foo) (default-value 'foo) ;; => "a" Immediately after this I run the ...
1
vote
1answer
493 views

Passing a symbol as an argument to a function

I'm trying to understand why this doesn't work, and how to make it work: (defvar test/var-1 nil) (defvar test/var-2 nil) (defun make-setter (var-to-set) (lambda (val-to-set) (setq var-to-set ...
0
votes
0answers
61 views

alist error when value created using (concat string1 string2) [duplicate]

I'm really confused with what's happening here. In my config for backups I've the line (setq backup-directory-alist '(("" . "~/.emacs.d/backup/per-save"))) and I've a defined a variable in my init....
0
votes
2answers
109 views

Warning assigning variables

I'm rebuilding my emacs configuration, and trying to compile without warnings. I'm using also cask. I have this case: (require 'magit) ;; Enable a right limit of 70 chars for git logs (add-hook '...
4
votes
2answers
273 views

Reflection on function argument signatures

Is there anything built into elisp for reflection on function argument signatures? I have used (length (cadr (symbol-function #'my/function))), but this notably fails on built-in C functions. I'm ...
4
votes
2answers
159 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 ...
0
votes
1answer
86 views

converting xemacs lisp to run in emacs [closed]

I have used xemacs for years and have a lot of lisp code I have written. Now I want to switch to emacs and convert all the lisp code over to work in emacs. This is on an winXP machine. I'm sure I am ...
4
votes
2answers
344 views

An efficient set data structure in elisp

Does elisp provide a builtin efficient set data structure, similar to set in Python and std::set in C++?
3
votes
2answers
199 views

How to evaluate a symbol in a lambda function when defining it?

For example, (lambda () (message "%s" x))) But I would like x to be evaluated -- the lambda function should always use that value, instead of the current value of x. How should I do it? Preferably ...
1
vote
1answer
81 views

When is it not possible to quote nil? [duplicate]

I've never quoted nil before, as I can't see any sense in doing that, but I just played around with some code and it seems that in most cases it is possible to quote nil without any effect. However ...
12
votes
1answer
1k views

Meaning of period in (. 123)

I learnt . /path/to/file in bash is used to execute a file. Just out of curiosity, I eval something like the following in Emacs (. 123) ⇒ 123 (read "(. 123)") ⇒ 123 It looks like Emacs ...