Are Extensible Programming Languages Coming?

gManZboy writes "Programming writer and instructor Greg Wilson is proposing that the next generation of programming languages will use XML to store not only such things as formatting (so you can see indentation your way, and I can see it my way, via XSLT) but even programmatic entities -- like: <invoke-expr method="myMethod"><evaluate>record</evaluate></invoke-expr>. Wacky, but perhaps wacky enough to be possible?"

Comments

Re:Is this guy serious?

[hasdikarlsam]

You mean, like Lisp has been capable of for the last thirty years?

I think you're looking for macros. Proper, Lisp macros, not the weak text-substitution nonsense C comes with. :D

Ooh, this story is great. Next on, how to reinvent the wheel - in XML!

Haskell is a language for writing languages.

[shapr]

This is a standard paradigm in the Haskell world. You write a new language that fits the problem domain. These are called Domain Specific Languages
For example, Simon Peyton-Jones wrote a combinator library to describe financial contracts and used it to describe the collapse of Enron. (With fascinating conclusions!)
Paul Hudak has written Dance and Haskore. Dance is a language that describes dance choreography, with a handy OpenGL viewer. Haskore is a music scoring language where code looks like:

> cMajScale = Tempo 2
> (line [c 4 en [], d 4 en [], e 4 en [], f 4 en [],
> g 4 en [], a 4 en [], b 4 en [], c 5 en []])

Languages, spoken or programming, or any other means of expression is most efficient when it fits the problem domain.

If this sort of thing interests you, Lambda The Ultimate is a good forum to learn more.

Re:Subtext

[groomed]

Unix geeks typically balk at non-textual files, but I blame it on a fundamental lack of imagination. You can have both! Rich source code can be represented as text -- it's just not convenient to edit it like text.

A format which is as flexible and comprehensive as you describe is not convenient to edit period. The problem is that every tool which wants to edit a small part of it needs to understand (or at least be aware of) all of it.

Want to calculate a line number? Have to parse and render the entire document. Want to generate a diff? Have to parse and render the entire document. Want to translate a string? Have to send the entire document to the translator and wait for it to come back. Want to post a code snippet for discussion? Have to create a new file, paste the code snippet, then upload the file, meaning all discussion gets separated from the code. Unless every browser/mail reader/whatever is changed to understand the format, but this just reiterates the point made above.

This is not to say that it wouldn't have its uses, but they'd be rather specialized, and you'd probably end up with only 1 or 2 programs which can actually fully understand the format, somewhat similar to the current situation with Flash and Squeak.

There are very good reasons why we have the functional decomposition we have today. It makes it easier to work with other people.