Another syntactic consideration is whether to allow bare keywords as identifiers after ::, just as we do after .. E.g.
MyModule::switch = true
thing.MyModule::as(.that)
My opinion is YES because there's no ambiguity here.
But I think allowing whitespaces after :: can cause confusions in parser. E.g.
Foo::
switch bar {
...
}
This Foo:: is probably an incomplete expression, or mistyped Foo: (statement label). But allowing whitespaces after :: would eat Foo::\nswitch as an expression, and the diagnostics will be confusing ("consecutive statements must be separated by ;" between switch and bar)
edit:
I thought it might be worth mentioning that . actually allows whitespaces before the member name, but only when it's balanced:
foo .
bar() // OK
But I consider this a bug, though it’s probably too late to change now. That said, I don't think we need to follow it.