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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.

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2
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3answers
229 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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0answers
28 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
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2answers
40 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
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1answer
80 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
57 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
95 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 ...
39
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9answers
5k 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 ...
0
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0answers
30 views

Is #'(lambda …) historical legacy? [duplicate]

(elisp) Anonymous Functions says The following forms are all equivalent: (lambda (x) (* x x)) (function (lambda (x) (* x x))) #'(lambda (x) (* x x)) Because (lambda ...) is the most concise, I ...
3
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1answer
101 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, ...
0
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0answers
64 views

Slime inspector for emacs lisp

I want to know, if there is some possibility of inspecting an object as slime inspector does. For example, using libyaml I get the following result, it worked well: ELISP> (yaml-read-from-string ...
2
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2answers
125 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
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1answer
93 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
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1answer
55 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
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1answer
49 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
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1answer
71 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
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1answer
111 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
167 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
268 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
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1answer
103 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
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2answers
94 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
462 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
433 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
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0answers
177 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 ...
6
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3answers
505 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
2k 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
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1answer
274 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
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1answer
350 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
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1answer
58 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
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1answer
71 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
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1answer
135 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
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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
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0answers
56 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
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0answers
133 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
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2answers
165 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
53 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
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2answers
414 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
430 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
57 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
104 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
257 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
151 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
312 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
187 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
79 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 ...
2
votes
3answers
189 views

Bringing a function into a lexical environment

I'm using a closure to keep track of some stuff to do with state; I want to be able to ‘include’ a function into that closure, so it can access the state. The only way this is possible is by creating ...
2
votes
1answer
133 views

Why is org-table-calc-current-TBLFM throwing Wrong type argument: integer-or-marker-p Error?

Why does my code generate the error when used with org-table? No error message when code used outside of org-table #+NAME: get-country-or-area-name #+HEADER: :var iso-alpha2-code="ca" #+HEADER: :...
0
votes
1answer
222 views

Define key inside dolist

I am trying to avoid duplicating code and also trying to avoid introducing unnecessary global symbols. So I tried to use let, dolist and lambda when defining the same keys in two different keymaps: (...
3
votes
2answers
208 views

apply partially last arg

Is there something like apply-partially (apply-partially FUN &rest ARGS) Return a function that is a partial application of FUN to ARGS. ARGS is a list of the first N arguments to pass to FUN. ...