From: Michael Heerdegen <michael_heerdegen@web.de>
To: Kaushal Modi <kaushal.modi@gmail.com>
Cc: Help Gnu Emacs mailing list <help-gnu-emacs@gnu.org>
Subject: Re: Using let-bound var inside pcase conditions
Date: Mon, 17 Apr 2017 22:33:39 +0200 [thread overview]
Message-ID: <87tw5mdba4.fsf@drachen> (raw)
In-Reply-To: <CAFyQvY2mmXaaC8kh6r6o5xZrtXSum8_oZ1G6Sfuaqy1WfuO+Ww@mail.gmail.com> (Kaushal Modi's message of "Mon, 17 Apr 2017 18:07:42 +0000")
Kaushal Modi <kaushal.modi@gmail.com> writes:
> (message "(bad) Value is %s." (pcase var
> (`nil "nil")
> (`,one "one")
> (`,two "two")
> (_ "none of the expected")))))
I also try this from time to time just to remember that it's wrong: the
first appearance of a symbol in a pcase pattern is never transformed
into an `eq'uality test. Sometimes that's surprising (especially in
backquote patterns), but that's how it's defined.
BTW, `nil is equivalent to 'nil, and `,symbol is equivalent to just
symbol as a pattern.
To your question: I guess the shortest correct pattern is
(pred (eq one))
Regards,
Michael.
next prev parent reply other threads:[~2017-04-17 20:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-17 18:07 Using let-bound var inside pcase conditions Kaushal Modi
2017-04-17 20:33 ` Michael Heerdegen [this message]
2017-04-17 20:40 ` Kaushal Modi
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