Re: dash.el [was: Re: Imports / inclusion of s.el into Emacs]

[Joost Kremers]

On Sun, May 10 2020, Alfred M. Szmidt wrote:
[threading macros]
> In these cases, I see absolutley no benefit of using ->, it just 
> makes
> it more "magical" for no particular reason.  

For sure, whether to use a threading macro is a large part 
personal preference, but IMHO they *can* make code more readable. 
Basically, you can convert:

  (print (eval (read)))

into:

   (-> (read)
     eval
     print)

The first form is backwards, in a way: `print` is written first, 
but it's what happens last. With `->` you can write the functions 
in the order in which they're executed.

For a longer discussion with more examples, see here: 
<https://yoo2080.wordpress.com/2014/02/23/threading-macros-from-dash-for-emacs-lisp/>

And I don't think it's been pointed out yet (though I may have 
missed some messages in this thread), that `->` and `->>` are part 
of Elisp since Emacs 25, except that they are called 
`thread-first` and `thread-last` (somewhat unfortunately, I 
believe, because they have nothing to do with CPU threads and are 
therefore unrelated to the other Elisp functions whose names start 
with `thread-`.)


--
Joost Kremers
Life has its moments