Pinderkent

An XML-like syntax is suitable for marking up other data. XHTML is a good example of an appropriate use of XML. There are numerous data transmission formats that make use of XML rather effectively. Even configuration files, to some extent, can be represented via XML. But one thing that should not be represented via an XML-like syntax is logic of the sort found in programming languages.

X# is a good example of why XML-based programming languages aren't a very good idea. One look at their X# sample programs should make it obvious why this is true. Any of those tasks could have been performed using a language like Perl or Python. But the Perl or Python equivalents would have been shorter, easier to read (and thus easier to maintain), and more portable. Many people often comment that Common LISP and Scheme have an awkward syntax to work with, but XML-based programming languages take that awkwardness to the next level, often without the benefits that LISP and Scheme do offer.

XML is best left as something a machine should process. It's not well-suited for humans to be reading and manipulating more than need be. It's especially not a good syntax to use for a programming language, especially one that offers non-declarative, imperative features. So I hope I never encounter XML-based programming languages like X# in practice.