Subject: bug#44205: [PATCH] Add new function seq-remove-item

From: "Basil L. Contovounesios" <[email-masked]>
Date: Tue, 27 Oct 2020 13:45:46 +0000

Stefan Kangas <[email-masked]> writes:

> diff --git a/lisp/emacs-lisp/seq.el b/lisp/emacs-lisp/seq.el
> index 4656277ea1..82daae6f48 100644
> --- a/lisp/emacs-lisp/seq.el
> +++ b/lisp/emacs-lisp/seq.el
> @@ -331,6 +331,13 @@ seq-remove
>    (seq-filter (lambda (elt) (not (funcall pred elt)))
>                sequence))
>  
> +;;;###autoload
> +(cl-defgeneric seq-remove-item (item sequence)
> +  "Return a list of all the elements in SEQUENCE that are not ITEM.
> +The comparison is done using `equal'. "
> +  (seq-filter (lambda (elt) (not (equal item elt)))
> +           sequence))

Why not replace seq-filter with seq-remove and do away with the 'not'?

Is the indentation right here?

>  ;;;###autoload
>  (cl-defgeneric seq-reduce (function sequence initial-value)
>    "Reduce the function FUNCTION across SEQUENCE, starting with INITIAL-VALUE.
> diff --git a/lisp/emacs-lisp/shortdoc.el b/lisp/emacs-lisp/shortdoc.el
> index acc7d13195..20cfd6e295 100644
> --- a/lisp/emacs-lisp/shortdoc.el
> +++ b/lisp/emacs-lisp/shortdoc.el
> @@ -730,6 +730,8 @@ sequence
>     :eval (seq-filter #'numberp '(a b 3 4 f 6)))
>    (seq-remove
>     :eval (seq-remove #'numberp '(1 2 c d 5)))
> +  (seq-remove-item
> +   :eval (seq-remove-item 3 '(1 2 3 4 5)))
>    (seq-group-by
>     :eval (seq-group-by #'cl-plusp '(-1 2 3 -4 -5 6)))
>    (seq-difference
> diff --git a/lisp/tab-line.el b/lisp/tab-line.el
> index 46bf89f14e..26f5f750b4 100644
> --- a/lisp/tab-line.el
> +++ b/lisp/tab-line.el
> @@ -385,11 +385,11 @@ tab-line-tabs-window-buffers
>  variable `tab-line-tabs-function'."
>    (let* ((window (selected-window))
>           (buffer (window-buffer window))
> -         (next-buffers (seq-remove (lambda (b) (eq b buffer))
> -                                   (window-next-buffers window)))
> +         (next-buffers (seq-remove-item buffer
> +                                        (window-next-buffers window)))
>           (next-buffers (seq-filter #'buffer-live-p next-buffers))
> -         (prev-buffers (seq-remove (lambda (b) (eq b buffer))
> -                                   (mapcar #'car (window-prev-buffers window))))
> +         (prev-buffers (seq-remove-item buffer
> +                                        (mapcar #'car (window-prev-buffers window))))
>           (prev-buffers (seq-filter #'buffer-live-p prev-buffers))
>           ;; Remove next-buffers from prev-buffers
>           (prev-buffers (seq-difference prev-buffers next-buffers)))
> @@ -622,10 +622,10 @@ tab-line-select-tab
>  
>  (defun tab-line-select-tab-buffer (buffer &optional window)
>    (let* ((window-buffer (window-buffer window))
> -         (next-buffers (seq-remove (lambda (b) (eq b window-buffer))
> -                                   (window-next-buffers window)))
> -         (prev-buffers (seq-remove (lambda (b) (eq b window-buffer))
> -                                   (mapcar #'car (window-prev-buffers window))))
> +         (next-buffers (seq-remove-item window-buffer
> +                                        (window-next-buffers window)))
> +         (prev-buffers (seq-remove-item window-buffer
> +                                        (mapcar #'car (window-prev-buffers window))))

As others have pointed out, these would be better served by remq, and/or
fusing multiple loops into a single one.

Thanks,

-- 
Basil