Finding Java Grammars

I'm making my way into Rascal - nice work!

I'm halfway through the Tutor and might be getting ahead of myself, but one of my interests is refactoring Java. I've watched Tijs van der Storm's Curry On 2016 talk where he presents an example of this (the "TrafoFields" module around minute 16 in the video).

I was eager to get into this kind of work so I searched the documentation for the Java grammar and a similar example using it, to no avail. What's more, the library documentation has under lang::java only m3 and jdt. I reloaded Tijs' video to find he uses lang::java::\syntax::Java15. I blindly tried importing that in the Repl and it worked (albeit with lots of warnings)! I opened the Rascal .jar file to find there is even more in this package.

So my questions in this context are:

Why is this not in the documentation? I would have expected that the library documentation is exhaustive. Couldn't you at least add "TrafoFields" to the recipes?!
Is there an alternative way of finding out about such modules besides the online documentation (and apart from searching the .jar file)?
What is this weird backslash in the module name before "syntax", ::\syntax?

Solution

All good questions; and also implied suggestions for improvement. In the meantime if you get stuck please ask more questions.

Short answer: we've prioritized documenting what is used most and what is used in courses at universities and then what we've received questions about. So thanks for asking.

In reverse order:

The backslash is a generic escape to use identifiers in Rascal which are also keywords in the language. So any variable or package name or module name could be named "if" but you'd have to escape it. This helps a lot when defining abstract syntax trees for programming languages, as you can imagine where "if" would be a great name for an ast node type. "Syntax" happens to be a keyword in Rascal too.
The Rascal explorer view in eclipse can be used to browse through the library interactively. Also you can crawl the library using util::FileSystem and get a first class representation of everything that is in a library like |std:///|. Agreed, these are poorman's solutions and a good feature would a fully indexed searchable library. We're halfway there (see the analysis::text:: Lucene pre-work we've done towards supporting this.
That is a rhetorical question which I accept as a suggestion for improvement 😉😊 the answer is yes.