Re: Looking for new language features

"Randall Hyde" <rhyde@cs.ucr.edu> wrote in message
> > [New syntax added on the fly? Lots of dead extensible languages from
> > the 1970s like EL/1 and IMP72. -John]
>
> I can see why you're so down on IMP. I haven't used it personally,
> but it looks like every program you want to write requires a set of
> productions to generate the source language you wish to work in. [snip]
>
>However, keeping in mind that this language is now nearly 30 years
>old, and most people find 30-year old languages to be distasteful
>anyway, I'm wondering if the concept of a syntax-extensible language
>couldn't be brought up to date.
>
> For my own purposes, I'm not interested in a language that forces you
> to supply a grammar with every source file you supply. I'd be more
> interested in a tool that lets me easily write DSELs (domain specific
> embedded languages). Specfically, I'd like to have a full featured
> imperative language like C or Pascal (hey, 30-year old languages!)
> that could be used to write real programs "out of the box" plus the
> ability to add control constructs, data types, and other syntactical
> elements as appropriate for a given problem domain.


Microsoft's "Intentional Programming" research tool is intended to be
exactly such a beast. An "intention" is an extension to the base
language, that is mapped to the base language by "user-defined"
transformation rules ("reduction rules"). IP avoids "adding syntax
rules" by adding "intention objects" instead, which I think of as
simply new AST node types, and providing a direct-AST-manipulation
editor for "easy entry" of such new node types. However, the language
extending engineer still gets to provides "new information" (AST node
type, editing rules, semantic checking rules, reduction rules, all
these latter procedurally). And somehow, I don't see how you can
avoid adding new information if you wish to have new constructs.


You can do this with our DMS Reengineering Toolkit, too, in a bit more
traditional way: modify the base language grammar, and then add the
remaining information by a combination of procedural code and
declarative transforms and attribute evaluators.
--
Ira Baxter, Ph.D., CTO idbaxter@semdesigns.com 512-250-1018x140
Semantic Designs, Inc., www.semdesigns.com FAX 512-250-1191
12636 Research Blvd #C214, Austin, Texas 78759
[Does anyone actually do syntax extension? If so, is it useful? -John]

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