From: Tom Lane <tgl@sss.pgh.pa.us>
To: Bruce Momjian <bruce@momjian.us>
cc: brian.williams@mayalane.com, pgsql-docs@lists.postgresql.org
Subject: Re: Nit: "Immutable" should be "pure"
In-reply-to: <20191107172830.GD12478@momjian.us>
References: <157313627814.14272.6307248648194149757@wrigleys.postgresql.org>
 <20191107172830.GD12478@momjian.us>
Comments: In-reply-to Bruce Momjian <bruce@momjian.us>
	message dated "Thu, 07 Nov 2019 12:28:30 -0500"
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Date: Thu, 07 Nov 2019 12:38:11 -0500
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Bruce Momjian <bruce@momjian.us> writes:
> On Thu, Nov  7, 2019 at 02:17:58PM +0000, PG Doc comments form wrote:
>> The adjective "immutable" describing the functions and operators used in an
>> index (see two occurrences in doc snippet below) is incorrect and should be
>> replaced with "pure".

> I think the best we can do is to mention that IMMUTABLE functions mean
> pure, but I am not sure there is even enough demand for that, vs.
> confusing people.

Yeah.  I don't think this terminology is nearly as universal
as the OP believes, so I don't feel a need to change anything.

If we adopt Corey's proposal to create a glossary [1], there'd be
room for a parenthetical comment like "(In some circles, "pure" is the
preferred term for this function property.)" in the glossary entry for
"immutable".  I suspect it won't be the only entry that needs
cross-references to other terminology.

			regards, tom lane

[1] https://commitfest.postgresql.org/25/2305/