An alternative to "restricted keywords" + helping automatic modules

John Rose john.r.rose at
Fri May 19 04:24:29 UTC 2017

On May 18, 2017, at 1:59 AM, Stephan Herrmann <stephan.herrmann at> wrote:
> In all posts I could not find a real reason against escaping,
> aside from aesthetics. I don't see this as sufficient motivation
> for a less-then-perfect solution.

So, by disregarding esthetics...
> Clarity:
> I'm still not completely following your explanations, partly because
> of the jargon you are using. I'll leave it to Alex to decide if he
> likes the idea that JLS would have to explain terms like dotted
> production.
> Compare this to just adding a few more rules to the grammar,
> where no hand-waving is needed for an explanation.
> No, I did not say that escaping is a pervasive change.
> I never said that the grammar for ordinary compilation units
> should be changed.
> If you like we only need to extend one rule for the scope of
> modular compilation units: Identifier. It can't get simpler.
> Completeness:
> I understand you as saying, module names cannot start with
> "transitive". Mind you, that every modifier that will be added
> to the grammar for modules in the future will cause conflicts for
> names that are now legal, and you won't have a means to resolve this.
> By contrast, we can use the escaping approach even to solve one
> more problem that has been briefly touched on this list before:
> Automatic modules suffer from the fact that some artifact names may
> have Java keywords in their name, which means that these artifacts
> simply cannot be used as automatic modules, right?
> Why not apply escaping also here? *Any* dot-separated sequence
> of words could be used as module name, as long as module references
> have a means to escape any keywords in that sequence.
> Suitability for implementation:
> As said, your proposal resolves one problem, but still IDE
> functionality suffers from restricted keywords, because scanning
> and parsing need more context information than normal.

…we obtain the freedom for IDEs to disregard abnormal
amounts of context, saving uncounted machine cycles,

> - Recovery after a syntax error will regress.

…and we make life easier for all ten writers of error recovery

> - Scanning arbitrary regions of code is not possible.

…we unleash the power of an army of grad students to study
bidirectional parsing of module files,

> Remember:
> In an IDE code with syntax errors is the norm, not an exception,
> as the IDE provides functionality to work on incomplete code.

…and ease the burdens of the thousands who must spend their
time looking at syntax errors for their broken module files.

Nope, not for me.  Give me esthetics, please.  Really.

— John

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