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

[Oleh Krehel <ohwoeowho@gmail.com>]

Nicolas Petton <nicolas@petton.fr> writes:

> Oleh Krehel <ohwoeowho@gmail.com> 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?
>

I like `seq-group-by`.

I'm not sure about `seq-mapcat`, since there is `cl-mapcan` (although
it's destructive), I guess `seq-mapcat` would be fine.

And I would prefer the name `seq-partition` instead of `seq-slice`,
since `partition' is a Clojure name with same effect, and slice means
something different in Python.

Oleh