Re: Output an alist from a function

[Stephen Berman <stephen.berman@gmx.net>]

On Mon, 23 Sep 2024 21:42:38 +0000 Heime <heimeborgia@protonmail.com> wrote:

> I have an alist composed of keys and associated directory paths, and want
> to output an alist made of the same keys with values being a validation flag.
> Perhaps the problem is the call to mapcar.  In the case of the hash table I have
> to call output-table after the maphash.
>
> (defun dirpath-validation (input-table-or-alist)
>   "Test validity of directory path for each key."
>
>   (cond
>
>       ((hash-table-p input-table-or-alist)
>
>       ;; Make hash-table for output
>       (let ( (output-table (make-hash-table :test 'equal)) )
>         (maphash (lambda (key dirpath)
>                    (puthash key (not (file-directory-p dirpath)) output-table))
>                  input-table-or-alist)
>         output-table))
>
>       (t
>          (mapcar (lambda (entry)
>               (let ( (key      (car entry))
>                      (dirpath  (cdr entry)) )
>                 (cons key (not (file-directory-p dirpath)))) )
>             input-table-or-alist)) ))

I get this:

(dirpath-validation #s(hash-table data ("a" "/usr" "b" "file")))
==> #s(hash-table test equal data ("a" nil "b" t))

(dirpath-validation '(("a" . "/usr") ("b" . "file")))
==> (("a") ("b" . t))

What's the problem?

Steve Berman