Re: `append' vs. `nconc'

[Emanuel Berg <embe8573@student.uu.se>]

Teemu Likonen <tlikonen@iki.fi> writes:

> NCONC doesn't touch the elements (i.e., CAR values
> of conses) so this is fine:
>
>     (setq foo (nconc (list '(a . 1) '(b . 2)) foo))

OK!

Because, many cases where I replaced `apply' by
`nconc' were lists of lists.

What is the reason one has to use `list'? (I suppose
the ` isn't safe, either.)

And: In Pascal's examples he always used `setf'.
The help says it can be used for places as well as for
symbols. In the examples tho there has been only
symbols if I'm not mistaken.

(setq completion-ignored-extensions
      (nconc completion-ignored-extensions (list ".bcf" ".run.xml")) )

(setq ispell-skip-region-alist
      (nconc ispell-skip-region-alist (list '("`" . "\\(`\\|'\\)"))) )

(let*((write
       (list
         '("hp"       "http://user.it.uu.se/~embe8573")
         '("lenght"   "length")
         ;; ...
         '("thedate"  "" (lambda () (interactive) (show-time-and-date t))) ; INSERT
         ))
      (groups (list
                '("ctt" "comp.text.tex")
                '("geg" "gmane.emacs.gnus")
                ;; ...
                ))
      (both (nconc write groups)))
  (define-abbrev-table 'global-abbrev-table both) )

(let ((modes (list
     '("\\.bal\\'"  . balance-mode)
     '("\\.gpi\\'"  . gnuplot-mode)
     ;; ...
     )))
  (setq auto-mode-alist (nconc modes auto-mode-alist)) )

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