[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
bug#31311: 27.0; doc of `pcase'
From: |
Thien-Thi Nguyen |
Subject: |
bug#31311: 27.0; doc of `pcase' |
Date: |
Tue, 15 May 2018 16:24:44 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) |
() Michael Heerdegen <michael_heerdegen@web.de>
() Sat, 12 May 2018 15:54:18 +0200
> a. (pcase t ('t 'true)) => true
> b. (pcase nil ('nil 'false)) => false
> c. (pcase t (t 'true)) => true
> d. (pcase nil (nil 'false)) |= ERROR: Unknown pattern ‘nil’
That's all correct and intended - see 3ef31167. t was
originally intended as catchall pattern equivalent to _ but
has been deprecated (since it was confusing). Try e.g.
(pcase nil
(t t))
You get a message when you use it, but when evaluating and
not when compiling (so you must look in the *Messages* buffer
- I don't think this is intended...). A catch-nothing
pattern is not useful, so nil is just invalid.
Thanks. I've added a blurb suggesting to avoid both ‘t’ and
‘nil’ (commit 5fc0f24c). Here's the text:
Two symbols to avoid are @code{t}, which behaves like @code{_}
(above) and is deprecated, and @code{nil}, which signals error.
It makes no sense to bind these (@pxref{Constant Variables}).
This is in the table, part of the @var{symbol} entry.
--
Thien-Thi Nguyen -----------------------------------------------
(defun responsep (query)
(pcase (context query)
(`(technical ,ml) (correctp ml))
...)) 748E A0E8 1CB8 A748 9BFA
--------------------------------------- 6CE4 6703 2224 4C80 7502
signature.asc
Description: PGP signature
- bug#31311: 27.0; doc of `pcase', Thien-Thi Nguyen, 2018/05/01
- bug#31311: 27.0; doc of `pcase', Thien-Thi Nguyen, 2018/05/12
- bug#31311: 27.0; doc of `pcase', Michael Heerdegen, 2018/05/12
- bug#31311: 27.0; doc of `pcase',
Thien-Thi Nguyen <=
- bug#31311: 27.0; doc of `pcase', Michael Heerdegen, 2018/05/15
- bug#31311: 27.0; doc of `pcase', Thien-Thi Nguyen, 2018/05/16
- bug#31311: 27.0; doc of `pcase', Michael Heerdegen, 2018/05/16
- bug#31311: 27.0; doc of `pcase', Thien-Thi Nguyen, 2018/05/23
- bug#31311: 27.0; doc of `pcase', Drew Adams, 2018/05/23
- bug#31311: 27.0; doc of `pcase', Eli Zaretskii, 2018/05/23
- bug#31311: 27.0; doc of `pcase', Eli Zaretskii, 2018/05/23
- bug#31311: 27.0; doc of `pcase', Thien-Thi Nguyen, 2018/05/23
- bug#31311: 27.0; doc of `pcase', Eli Zaretskii, 2018/05/24
- bug#31311: 27.0; doc of `pcase', Thien-Thi Nguyen, 2018/05/26