Comments on: The Two Meanings of Declarative http://cdsmith.wordpress.com/2007/06/28/the-two-meanings-of-declarative/ software, programming languages, and other ideas Tue, 17 Nov 2009 16:15:58 +0000 http://wordpress.com/ hourly 1 By: Top Posts « WordPress.com http://cdsmith.wordpress.com/2007/06/28/the-two-meanings-of-declarative/#comment-56 Top Posts « WordPress.com Fri, 29 Jun 2007 23:59:26 +0000 http://cdsmith.wordpress.com/2007/06/28/the-two-meanings-of-declarative/#comment-56 [...] The Two Meanings of Declarative For about the seventh time, now, I’ve been “corrected” on something in a way that isn’t really […] [...] [...] The Two Meanings of Declarative For about the seventh time, now, I’ve been “corrected” on something in a way that isn’t really […] [...]

]]> By: Jonathan Allen http://cdsmith.wordpress.com/2007/06/28/the-two-meanings-of-declarative/#comment-55 Jonathan Allen Fri, 29 Jun 2007 15:38:30 +0000 http://cdsmith.wordpress.com/2007/06/28/the-two-meanings-of-declarative/#comment-55 Your knowledge of SQL seems to be limited to one-liners. Most versions of SQL support things like variables and functions, the like of which you won't see in a declarative language. SQL is generally thought as primarily a set based langauge with procedural capabilities. A declarative language would be something like XSLT, ASP.NET markup, HTML, or XAML. In these langauges the code closely resembles the results. Things like order of execution are hard to determine, but that usually doesn't matter much. Take XSLT for instance. It rarely matters if the transformation starts from the first XML element or the last, you will get the same result. Now compare that to a sequence of SQL statements. If one performs an update before a select they will get a very different result than if the select comes first. Your knowledge of SQL seems to be limited to one-liners. Most versions of SQL support things like variables and functions, the like of which you won’t see in a declarative language. SQL is generally thought as primarily a set based langauge with procedural capabilities.

A declarative language would be something like XSLT, ASP.NET markup, HTML, or XAML. In these langauges the code closely resembles the results. Things like order of execution are hard to determine, but that usually doesn’t matter much. Take XSLT for instance. It rarely matters if the transformation starts from the first XML element or the last, you will get the same result.

Now compare that to a sequence of SQL statements. If one performs an update before a select they will get a very different result than if the select comes first.

]]> By: Neil Mix http://cdsmith.wordpress.com/2007/06/28/the-two-meanings-of-declarative/#comment-53 Neil Mix Fri, 29 Jun 2007 14:14:46 +0000 http://cdsmith.wordpress.com/2007/06/28/the-two-meanings-of-declarative/#comment-53 Haskell and SQL are similar languages in that their execution produces no side-effects -- there's no way to programmatically alter memory or program state (Haskell nomads being the intentional exception). I think that's the meaning of declarative that you're seeking. Some people refer to this as "functional" programming, but that's not quite correct, as many languages have first-class functions but also rely on side-effects. Haskell and SQL are similar languages in that their execution produces no side-effects — there’s no way to programmatically alter memory or program state (Haskell nomads being the intentional exception). I think that’s the meaning of declarative that you’re seeking. Some people refer to this as “functional” programming, but that’s not quite correct, as many languages have first-class functions but also rely on side-effects.

]]> By: Ivan Tikhonov http://cdsmith.wordpress.com/2007/06/28/the-two-meanings-of-declarative/#comment-52 Ivan Tikhonov Fri, 29 Jun 2007 08:49:33 +0000 http://cdsmith.wordpress.com/2007/06/28/the-two-meanings-of-declarative/#comment-52 'Declarative' is a buzzword. Read http://en.wikipedia.org/wiki/Declarative_language ‘Declarative’ is a buzzword.

Read http://en.wikipedia.org/wiki/Declarative_language

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