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"The starting list count" ?????
From: |
Alan Mackenzie |
Subject: |
"The starting list count" ????? |
Date: |
Mon, 3 Jan 2022 17:49:40 +0000 |
Hello, Emacs.
I'm trying to make sense of the form whose printed syntax is
(1 . #1)
which arises in the Emacs test suite file seq-tests.el. I'm having
difficulty.
The Elisp manual page "Special Read Syntax" says about it:
`#N'
When printing circular structures, this construct is used to
represent where the structure loops back onto itself, and `N' is
the starting list count:
(let ((a (list 1)))
(setcdr a a))
=> (1 . #0)
.. What does this mean, please? What does "is the starting list count"
mean? There is only one "list", so what is the "list count"?
Clearly the N in #N is counting something, but what? What is the
meaning of
(1 . #1)
? What is it about the description in the manual which is so perplexing
me?
Help!
--
Alan Mackenzie (Nuremberg, Germany).