new `pcase-let' syntax hotter than TikTok girls?

new `pcase-let' syntax hotter than TikTok girls?

[Emanuel Berg]

Check out this syntax with `pcase-let'! :O

(pcase-let ((`(,up ,down) (if button
                             `(,#'backward-button ,#'forward-button)
                           `(,#'previous-line ,#'forward-line) ))) ... )

Advantage: A single test (here, `if') but without the bulky
and ugly combo with `let*' and `car'/`cadr' ...

Here is an example how it can be used, and actually is used already [1]

(defun set-vertical-keys (kmap &optional button np tab)
  (pcase-let ((`(,up ,down) (if button
                               `(,#'backward-button ,#'forward-button)
                             `(,#'previous-line ,#'forward-line) )))
    (define-key kmap "i" up)
    (define-key kmap "k" down)
    (when np
      (define-key kmap "p" up)
      (define-key kmap "n" down) )
    (when tab
      (define-key kmap [backtab] up)
      (define-key kmap "\t"      down) )))

and then for example [2]

(let ((kmap Buffer-menu-mode-map))
  (set-vertical-keys kmap nil nil t)
  ;; ...
  )

Too sexy for its shirt!

[1] https://dataswamp.org/~incal/emacs-init/scroll.el
[2] https://dataswamp.org/~incal/emacs-init/buffer-menu.el

-- 
underground experts united
https://dataswamp.org/~incal

Re: new `pcase-let' syntax

[Philip Kaludercic]

Emanuel Berg <incal@dataswamp.org> writes:

> Check out this syntax with `pcase-let'! :O
>
> (pcase-let ((`(,up ,down) (if button
>                              `(,#'backward-button ,#'forward-button)
>                            `(,#'previous-line ,#'forward-line) ))) ... )

In what sense is this new?

I also get the feeling this is a hack for the sake of a hack.  Is it
really that much better than the "classical"

--8<---------------cut here---------------start------------->8---
(let ((up #'previous-line) (down #'forward-line))
  (when button
    (setq up #'backward-button down #'forward-button))
  ;; ...
  )
--8<---------------cut here---------------end--------------->8---

RE: [External] : Re: new `pcase-let' syntax

[Drew Adams]

> > (pcase-let ((`(,up ,down)
> >             (if button
> >                 `(,#'backward-button ,#'forward-button)
> >               `(,#'previous-line ,#'forward-line)))) ...)
> 
> In what sense is this new?
> I also get the feeling this is a hack for the sake of a hack.  Is it
> really that much better than the "classical"
> 
> (let ((up #'previous-line) (down #'forward-line))
>   (when button (setq up #'backward-button down #'forward-button))...)

It gives you more opportunities to
use your `,', ``', and `)' keys?

Re: [External] : Re: new `pcase-let' syntax

[Emanuel Berg]

Drew Adams wrote:

>>> (pcase-let ((`(,up ,down)
>>>             (if button
>>>                 `(,#'backward-button ,#'forward-button)
>>>               `(,#'previous-line ,#'forward-line)))) ...)
>> 
>> [...] I also get the feeling this is a hack for the sake of
>> a hack. Is it really that much better than the "classical"
>> 
>> (let ((up #'previous-line) (down #'forward-line))
>>   (when button (setq up #'backward-button down #'forward-button))...)
>
> It gives you more opportunities to use your `,', ``', and
> `)' keys?

Okay, so how do you do this the classical way then?

(pcase-let*((`(,sail ,ho) (if t '(1 2) '(3 4)))
            (msg (format "%s is %s" sail ho)) )
  msg)

Also, it's better than `let' and `setq' because if you make
a typo setq creates a global variable, a bug that silently
enters your code.

Obviously if you gonna do typos all day ever day that's gonna
be a problem even with pcase-let LOL

-- 
underground experts united
https://dataswamp.org/~incal