• From: "stephengreenubl@g..." <stephengreenubl@g...>
• To: "Michael Ludwig" <milu71@g...>
• Date: Sat, 10 Apr 2010 21:17:57 +0000

Is any declarative language a programming language? Isn't any computer-related language useful for describing a desired state or behaviour or both potentially a declarative language? I think of query languages like SQL and assertion languages and AI languages like OWL, RDF and SPARQL. Many of these are executed. They all just describe data and/or behaviours. I'd regard a schema as a set of assertions. Maybe any set of assertions can be said to be written in a declarative language, especially but perhaps not exclusively, those which can be automatically executed. Maybe the original computing concepts of Llull and later Leibnitz, etc were declarative and the concept of a program came later and the two concepts developed side by side as computing and information  science took shape.

Stephen D Green



-----Original Message-----
From: Michael Ludwig
Sent:  10/04/2010 9:56:49 pm
Subject:  Re:  RE: Declarative programming requires a different mindset

Hi Roger,

Costello, Roger L. schrieb am 10.04.2010 um 13:28:52 (-0400)
[ RE: Declarative programming requires a different mindset]:
> 
> I continue to explore the declarative programming mindset. I've had a
> few more insights. I realized, for example, that XML Schema, RELAX NG,
> and Schematron are declarative programming languages.

The schema languages you're listing here are certainly declarative in
that you declare what you want your data to look like (instead of
painstakingly write code to walk your data and check each bit of it,
which is what the processor does for you), but they simply aren't
programming languages.

> I wrote a summary of my insights:
> 
> http://www.xfront.com/XML-Declarative-Programming/
> 
> I welcome your comments.

  "XHTML is a declarative programming language."

It's not a programming language.

In my own and personal experience, any insight into high-level concepts
such as "declarativeness" has only emerged after considerable practice,
as the result of going wrong, getting stuff done, leaning back, maybe
reflecting on things, maybe just experiencing a revelation.

Personally, again, I would say that it's okay to proceed like that: Work
and practice, don't care too much about theoretical insight; it will
eventually come to you just naturally as the result of reflection once
you've practiced enough.

But YMMV, of course :-)
-- 
Michael Ludwig

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