Re: [xml-dev] Create a special purpose programming language, in XML, usi

[Norman Gray <norman@astro.gla.ac.uk>]

David, hello.

On 2013 Oct 18, at 15:12, David Lee wrote:

> I would say that is roughly accurate to my understnding ... which is why small XSLT programs are reasonably manageable to me, but largish ones become incomprehensible ... where your '8 different method signatures' becomes '10,000 different method signature'
> 
> Yet a very large number of people are extremely happy and successful at working with XSLT which leads me to belive I must be missing a mental model that makes it comprehensible.

That's pretty much my experience.  XSLT ticks a lot of my nice-programming-language boxes, in principle -- I like XSLT -- but when I actually come to use it, and when a project gets above a certain size, I usually end up gnashing my teeth and swearing nastily.

Random observations:

  * The nastiness may be a strong function of the structure of the XML being processed.  Highly structured and 'orthogonal' XML is going to be a lot nicer to process, with fewer modes and fancy selectors required, but that may be rare.

  * There aren't many up-front structuring/packaging mechanisms within XSLT, to help authors manage and compartmentalise code.  Yes, one can include stylesheets, but that's not importantly different from textual inclusion, so there's not a lot of real packaging here.

  * XSLT is just plain ugly, both in the sense of being 'jaggy' to read on the screen, and being verbose, so that you don't get that much real code onto a screen in an editor window, so that I, at least, find it easy to get lost within a file.  I've whined about this on this list, at various intervals, for about a decade (sorry, people -- I'm still taking the medicine), without anyone showing much sign of agreeing with me.  I've even gone to the extent of creating an alternative syntax, so great was my irritation <http://nxg.me.uk/dist/lx/>, but I've never had many takers.  Oh well....

One good counter here, which I can't disprove, is that if you spend a lot of time looking at XSLT, then your eyes adjust and you stop seeing the pointy brackets and end-tags; but (a) that only works if you spend a _lot_ of time with it, and (b) 'you eventually get used to it' is never a good recommendation for a language.

All the best,

Norman


-- 
Norman Gray  :  http://nxg.me.uk
SUPA School of Physics and Astronomy, University of Glasgow, UK