From: Stefan Monnier <monnier@iro.umontreal.ca>
To: MON KEY <monkey@sandpframing.com>
Cc: 6878@debbugs.gnu.org
Subject: bug#6878: bool-vectors of length 0 signal error when aref/aset the 0th element
Date: Thu, 19 Aug 2010 17:51:51 +0200 [thread overview]
Message-ID: <jwv1v9uzjrj.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <AANLkTimEZqsnK=s2ySmW2MWNd9-rRRhzgRSvRQZhyZT5@mail.gmail.com> (MON KEY's message of "Thu, 19 Aug 2010 10:13:42 -0400")
>>> ,---- (info "(elisp)Bool-Vector Type")
>>> | "A "bool-vector" is a one-dimensional array of elements that must be `t'
>>> | or `nil'."
>> All elements of (make-bool-vector 0 t) are either t or nil.
> Prove it!
Easy! formally, he said:
∀ n ≥ 0 ∧ n < 0. (aref (make-bool-vector 0 t) n) ∈ { nil, t }
And since there is no such `n', this is trivially true.
More specifically, "n ≥ 0 ∧ n < 0" is a falsehood, and from false you
can conclude anything you wish. Among other things you can just
a trivially prove:
∀ n ≥ 0 ∧ n < 0. the sky is green
-- Stefan
next prev parent reply other threads:[~2010-08-19 15:51 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-18 4:19 bug#6878: bool-vectors of length 0 signal error when aref/aset the 0th element MON KEY
2010-08-18 7:36 ` Stefan Monnier
2010-08-19 1:51 ` MON KEY
2010-08-19 8:42 ` Andreas Schwab
2010-08-19 14:13 ` MON KEY
2010-08-19 15:51 ` Stefan Monnier [this message]
2010-08-19 17:06 ` MON KEY
2010-08-19 14:47 ` Stefan Monnier
2010-08-19 15:04 ` Andreas Schwab
2010-08-19 16:18 ` Chong Yidong
2010-08-19 17:09 ` MON KEY
2010-08-19 18:40 ` Juanma Barranquero
2010-08-19 23:24 ` Chong Yidong
2010-08-20 2:01 ` MON KEY
2010-08-20 2:23 ` Juanma Barranquero
2010-08-20 18:01 ` MON KEY
2010-08-20 19:49 ` Juanma Barranquero
2010-08-20 23:06 ` MON KEY
2010-08-20 13:02 ` Stefan Monnier
2010-08-20 18:44 ` MON KEY
2010-08-21 12:40 ` Kevin Rodgers
2010-08-21 15:53 ` Andreas Schwab
2010-08-21 17:02 ` MON KEY
2010-08-18 8:36 ` Andreas Schwab
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