Questions tagged [lexical-binding]

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Reliable lexical binding?

How does one reliably create a lexically bound/scoped variable? Consider the following: ;; -*- lexical-binding: t; -*- (let ((f load-file-name)) (defun foo () f)) Normally f would be lexically ...
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How do I call a function within a lambda?

I would like to define a function that generates lambdas, as such: (defun my-func (FUNCTION) (lambda () (FUNCTION))) But when I evaluate the following (defun my-func1 () (message &...
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What type of variable binding is setq creating?

What type of variable binding or variable or symbol is setq creating, when the variable hasn't been declared prior setq? Given following source code: ;; -*- lexical-binding: t; -*- (defun setq-x () ...
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7 votes
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How to make sure no global variables have been created in a piece of lisp code?

I am writing some lisp code and I would like it not to mess with the global variables in the system. I am therefore being very careful to only use variables within the scope of the let special form. ...
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lexical-binding: How to create a let-bound function that recursively calls itself

The custom function below my-jump-to works after being evaluated in a scratch buffer, but does not work when I stick it into a library with lexical-binding non-nil in the header. When byte-compiling, ...
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2 votes
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How can I enable lexical binding for Elisp code in org-mode?

I have the following code: #+begin_src elisp (setq lexical-binding t) (let ((a 1)) ; binding (1) (let ((f (lambda () (print a)))) (let ((a 2)) ; ...
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Why symbol-value throws a void-variable error with a let form if lexical binding is on? [duplicate]

Here's a simple example from the manual: ;; Here the symbol ‘abracadabra’ ;; is the symbol whose value is examined. (let ((abracadabra 'foo)) (symbol-value 'abracadabra)) ⇒ foo Why does this ...
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Lexical binding in a process filter

The code constantly prints server-process: nil instead of the server process name: -*- lexical-binding: t; -*- (let* ((port 1234) (server-process 'something)) (setq server-process (...
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1 vote
1 answer
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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? ...
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3 votes
1 answer
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Can I determine the difference of declaring (and not declaring) a file to use lexical-binding?

I have been trying to understand what difference it makes if you set the file variable lexical-binding to t for a particular source file. As mentioned in emacswiki that in order to use lexical-...
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Global lexical-binding setting?

I've seen ;;; -*- lexical-binding: t; -*- at the top of a file and (setq lexical-binding t) as how to turn on lexical binding for elisp code, but is there a way to tell Emacs to simply always do ...
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3 votes
2 answers
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byte-compile and lexical-binding

Could someone in the know please help me understand what's going on here: ;; -*- lexical-binding: t; -*- (let* ((a 0)) (let* ((a 1)) (funcall (byte-compile (lambda () a))))) ;;=> 0 wat? Not ...
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1 answer
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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, ...
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3 votes
3 answers
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How to avoid use of `lexical-let`

I have a macro that intends to creates a closure: ; -*- lexical-binding: t -*- (defmacro repro () (let ((kmap-sym (gensym "kmap-"))) `(let ((,kmap-sym (make-sparse-keymap))) (define-key ,...
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1 answer
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Using new features in emacs 27 generators

I want to try new features in emacs 26, I'm using emacs 27, generators and threads, but when I try to use on ielm buffer, I get the same error: ELISP> (iter-defun my-iter (x) (iter-yield (1+ (...
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  • 707
16 votes
3 answers
625 views

Defun inside let with lexical binding gives byte-compile warning "the function is not known to be defined"

I want to get the effect of a static variable by using defun inside of let with lexical binding to create a closure. However, when byte-compiling the file, I get a warning. Am I doing something wrong, ...
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Bind a function-local variable to an asynchronous lambda [duplicate]

In wakatime-mode, there are a bunch of process calls that is done by the wakatime-call function. It calls a predefined shell command, so no real magic inside. Now I’d like to make it a bit more error ...
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6 votes
1 answer
1k views

How to make local function binding for closure?

For example, when defining the natural number sequence stream, I can use ;; -*- lexical-binding: t; -*- (defun nats (n) (cons n (lambda () (nats (1+ n))))) (nats 0) => (0 closure ((n . 0) ...
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2 votes
1 answer
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lexical-binding only set at the buffer level?

According to this, it seems to say setting lexical-binding only happens at the individual buffer level, i.e. I could not do (setq lexical-binding t) in my init file and have it apply to all subsequent ...
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