Add a filter function to emacs

Add a filter function to emacs

[Rolando Pereira]

Hello,

I would like to know if there is a reason for the lack of a filter
function on the emacs code base.

According to the Elisp Cookbook on the Emacs Wiki, it seems that it
would be simple to implement:

  (defun my-filter (condp lst)
    (delq nil
          (mapcar (lambda (x) (and (funcall condp x) x)) lst)))
;; From http://www.emacswiki.org/emacs/ElispCookbook

Shouldn't this function be in the regular emacs code base (maybe in the
lisp/simple.el file)?

Is there any problem with it?

Re: Add a filter function to emacs

[Geoff Gole]

>
> I would like to know if there is a reason for the lack of a filter
> function on the emacs code base.
>

See remove-if and remove-if-not in cl.el.

Re: Add a filter function to emacs

[Deniz Dogan]

2010/7/7 Rolando Pereira <ei08150@fe.up.pt>:
> Hello,
>
> I would like to know if there is a reason for the lack of a filter
> function on the emacs code base.
>
> According to the Elisp Cookbook on the Emacs Wiki, it seems that it
> would be simple to implement:
>
>  (defun my-filter (condp lst)
>    (delq nil
>          (mapcar (lambda (x) (and (funcall condp x) x)) lst)))
> ;; From http://www.emacswiki.org/emacs/ElispCookbook
>
> Shouldn't this function be in the regular emacs code base (maybe in the
> lisp/simple.el file)?
>
> Is there any problem with it?
>
>

I brought this up some time ago as I found that many higher-order
functions were missing in (non-cl.el) Emacs. If I remember correctly,
it's the lack of lexical scoping that makes it difficult.

-- 
Deniz Dogan