Re: Would seq-range and seq-mapcat be useful?

[Nicolas Petton]

Oleh Krehel <address@hidden> writes:

> I'd like to have this:
>
>     (defun seq-group-by (fn lst)
>       (nreverse
>        (cl-reduce
>         (lambda (acc it)
>           (let* ((key (funcall fn it))
>                  (cell (assoc key acc)))
>             (if cell
>                 (setcdr cell (push it (cdr cell)))
>               (push (list key it) acc))
>             acc))
>         lst
>         :initial-value nil)))
>
>     (seq-group-by
>      #'car
>      '(("a" 1)
>        ("b" 2)
>        ("b" 5)
>        ("c" 1)))
>     ;; (("a" ("a" 1))
>     ;;  ("b" ("b" 5)
>     ;;       ("b" 2))
>     ;;  ("c" ("c" 1)))
>     (seq-group-by
>      #'cadr
>      '(("a" 1)
>        ("b" 2)
>        ("b" 5)
>        ("c" 1)))
>     ;; ((1 ("c" 1)
>     ;;     ("a" 1))
>     ;;  (2 ("b" 2))
>     ;;  (5 ("b" 5)))
>
> Is this already somewhere?

I don't think it is :)

I think I'm going with the following 3 additions to seq.el: `seq-mapcat',
`seq-group-by', and `seq-slice' (or `seq-partition'?).

What do you think?

Nico
-- 
Nicolas Petton
http://nicolas-petton.fr