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Re: The poor state of documentation of pcase like things.

From: Michael Heerdegen
Subject: Re: The poor state of documentation of pcase like things.
Date: Sun, 20 Dec 2015 14:33:07 +0100
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/25.0.50 (gnu/linux)

address@hidden (Phillip Lord) writes:

> Irrespective of whether you agree with this or not, what I would say is
> that the current requirement for ,_ is not obvious, and that it is a
> pcase "gotcha".

You know, I wanted to make the same suggestion a year ago.  ,_ looks
weird, I see all your arguments, they are all valid.

But how would that fit into the semantics we have?  _ is a pcase
pattern.  You would like it to be also a valid QPAT, matching anything.

This would mess up the semantics to the worse: `_ would
then be a pcase pattern matching anything.  Should '_ also match
anything?  But how to match the symbol _ then?  If not, why should `_ be
different from '_ when there is no unquoting involved?

Or should _ as a QPAT only behave different when used "not at toplevel"?
This would be horribly inconsequent: We would get two different types of
QPATs: toplevel QPATS, and non-toplevel-QPATS.  That would confuse
people even more, a pain to explain and to internalize.



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