OSLO Video Comments: Building Textual DSLs
Finally I got around to watch the final PDC video, the one on textual DSLs. I got feedback from Doug that they actually read my comments and take them into account (as far as they make sense :-)) so I guess I have to deliver the last set.
Ok, Intellipad is a prototype, it will move into VS.
They still use token definition, not scannerless parsing. Wonder how they'll be able to combine languages (I know they're working on it, Doug told me about it in an upcoming interview for SE Radio on OSLO :-))
Hm, this interleave stuff is nice!
So, the grammar thing can also include "syntax graph transformations" to "shape" the data in any way you like. Nice!
I wonder if it is possible to also automatically derive an MSchema from the grammar (à la Xtext)?
They define a list recursively ... I wonder whether a more succinct way of doing this? Although this valuesof(...) thing normalizes the recursive list to a flat one. Nice.
Ok, ok I am happy :-) They are able to define functions, i.e. parametrized Productions. So it is possible to factor out e.g. a "comma-separated list", and the use that for comma separated lists of all kinds of other syntaxes. Very nice!
By the way: the same question applied to the optional stuff. Writing an optional element as "Production => mand | mand "," opt" is quite cumbersume. Easier would be to write "Production => mand ("," opt)?"
They have attributes. Nice! E.g. they use it for example to color tokens, for example to make them "keyword-colored".
I have to say, I really like the interactive, interpreted way of defining grammars the way Intellipad supports it. Much better than the generative approach supported by ANTLR & Co.
The dynamic API in C# does not yet convince me. Much too verbose. Of course having a dynamic API (à la dynamic EMF) is very nice.
So.... there's only interpretation in OSLO, they say.... hm. In the final example, they show a language to define MSI files. And from the models, the *generate* WIX files (XML). So, this language is purpose-built for code generation. I guess they have an "interpreter" that WriteLn's XML to a file.... I guess, it won't be long until we see a code generation engine for OSLO. You can't really make do without it in practice. Hopefully it'll be a decent language, and not some adaptation of ASP.NET or something. OSLO guys, let me know if you need some inspiration :-)