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Re: Package.el and specifying alternative dependencies


From: Thien-Thi Nguyen
Subject: Re: Package.el and specifying alternative dependencies
Date: Wed, 12 Apr 2017 09:44:32 +0200
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/26.0.50 (gnu/linux)

() Kaushal Modi <address@hidden>
() Tue, 11 Apr 2017 22:37:29 +0000

       ;; It's *very* critical that the order of packages stays
       ;; the same in NEW-RET as in ORIG-RET. The `push' command
       ;; flips the order, so use `reverse' to flip the order
       ;; back to the original.

If you don't mind ‘cl’, you can also use ‘cl-remove-if’ instead.
Squinting a little, i see the removal predicate is essentially
set membership, which seems to indicate ‘cl-set-difference’.
Unfortunately, a quick scan of (info "(cl) Lists as Sets")
reveals no guarantees on order, and Common Lisp (per CLHS)
actively disclaims such guarantees.  So it goes...

-- 
Thien-Thi Nguyen -----------------------------------------------
 (defun responsep (query)
   (pcase (context query)
     (`(technical ,ml) (correctp ml))
     ...))                              748E A0E8 1CB8 A748 9BFA
--------------------------------------- 6CE4 6703 2224 4C80 7502

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