Highlighting of primitive types

[damon-kwok]

The last two Nones should be recognized as constants rather than types

None in the return value should be recognized as a type

[jemc]

Discussed this briefly in today's sync call.

Personally, to me it is not clear that these should be considered different syntax highlighting cases, especially given the "create sugar" that Pony has - any time you mention a type where a value is expected, it is understood to be MyType.create() - including the cases you mentioned above None.create().

So in that context, I wouldn't really consider these to be "constants" in the syntax highlighting sense - they are simply types in every case. So you may be able to sidestep the potential parsing confusion entirely if you're willing to give up on these being separately highlighted.