Re: PSQL commands: \quit_if, \quit_unless

From: Jim Nasby <Jim(dot)Nasby(at)BlueTreble(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>, Corey Huinker <corey(dot)huinker(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>, Andrew Dunstan <andrew(at)dunslane(dot)net>, PostgreSQL <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: PSQL commands: \quit_if, \quit_unless
Date: 2016-12-02 22:50:48
Message-ID: aa487d18-f326-f451-5bf1-52a2cdda2c53@BlueTreble.com
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On 12/2/16 9:24 AM, Robert Haas wrote:
> On Fri, Dec 2, 2016 at 11:12 AM, Corey Huinker <corey(dot)huinker(at)gmail(dot)com> wrote:
>> In order for me to understand how high the bar has been set, can you
>> (Robert/Tom mostly, but I welcome any responses) explain what you mean by
>> "full-blown expression language"? What constructs must it include, etc?
>
> I mostly mean it should be based on flex and bison, not "this is so
> simple I can just hand-roll it". I don't think it has much chance of
> staying that simple.

It might be worth looking at other simplistic languages for guidance.
bash comes to mind, though there's GPL issues there. csh/tcsh don't have
those problems, and perhaps some of their grammar could be stolen.

I find it interesting that this is kind of the opposite problem that
most pl's face: how to fit the database access paradigm into the
language with the minimal amount of extra effort for users.

http://cvsweb.netbsd.org/bsdweb.cgi/src/bin/csh/?only_with_tag=MAIN
https://github.com/tcsh-org/tcsh
--
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
Data in Trouble? Get it in Treble! http://BlueTreble.com
855-TREBLE2 (855-873-2532)

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