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Re: Doing something different for the last element of a sequence (partit
Re: Doing something different for the last element of a sequence (partition)?
Mon, 16 Nov 2020 11:40:37 +0000
Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux)
>> I have a list of URLs (all-urls) and I want to launch a
>> Firefox window for the first x URLs, then wait y seconds,
>> then launch another one, etc., and then prompt the user if
>> the source of URLs can be deleted (provided that everything
>> went smoothly).
>> If I do:
>> | (seq-doseq (firefox-urls (seq-partition (seq-sort all-urls #'string<) x))
>> | (apply 'call-process "firefox" nil "*firefox*" nil firefox-urls)
>> | (sleep-for y))
>> that works fine, except that it also waits for y seconds af-
>> ter the last launch.
> Or handle the first one as the special case (completely untested):
> (cl-do (((firefox-urls (seq-partition (seq-sort all-urls #'string<) x))
> (delay 0 y)))
> (sleep-for delay)
> (apply 'call-process "firefox" nil "*firefox*" nil firefox-urls))
Inspiration! I initially looked at seq-reduce, but dismiss-
ed it because I was focussing on the /last/ partition. But
it is rather simple:
| ((all-urls (mapcar 'number-to-string (number-sequence 1 25))))
| (message "all-urls = %S" all-urls)
| (lambda (not-first-call firefox-urls)
| (if not-first-call
| (message "Would sleep"))
| (message "firefox-urls = %S" firefox-urls)
| t) ;; Set not-first-call for subsequent calls.
| (seq-partition (seq-sort #'string< all-urls) 3)