Re: Output an alist from a function

[Heime <heimeborgia@protonmail.com>]

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On Thursday, September 26th, 2024 at 4:43 PM, tomas@tuxteam.de <tomas@tuxteam.de> wrote:

> On Wed, Sep 25, 2024 at 08:30:30PM +0000, Heime wrote:
> 
> [...]
> 
> > > Maphash "just" iterates over the key-value pairs. The naming is a bit
> > > inconsistent, yes.
> > 
> > Recognize the flaws in this school of thought. While it is acknowledged
> > that inconsistencies exist, the proposed solution is always to read more
> > documentation and conduct small experiments to figure things out
> > independently. This approach is highly inefficient [...]
> 
> 
> This may apply when you're designing a new system. On an old system,
> with nearly 40 years of history and lots of dependencies, there are
> limits to how quickly you can change things without breaking programs
> and users you haven't ever heard of.

For what I am doing, the problem is not acute and with your suggestion 
towards mapc, I made

       ;; Initialize an empty alist to hold output
       (let ( (output-alist '()) )
         ;; `mapc' iterates over an alist in a manner similar to how
         ;; `maphash' processes a hash table.
         (mapc (lambda (entry)
                 (let ( (waypt    (car entry))
                        (dir-path (cdr entry)) )
                   ;; Push the result to the front of the output alist
                   (push (cons waypt (not (file-directory-p dir-path)))
                         output-alist)))
               fpln)
         ;; Reverse the list to maintain the original order
         (reverse output-alist)))
 
> You'll always have inconsistencies. Removing them is an ongoing process
> which happens very carefully, and is in a steady state wrt introducing
> new ones.
> 
> At this stage, the evolution resembles that of human languages (which
> do have their sets of inconsistencies).

It is as Guy Steele used to describe a programming language.  I attended one
of his speeches. 
 
> You can try to build your own to get a feel of what's involved. It's
> harder than it seems.
> 
> Cheers
> --
> t