On Sep 30, 2017, at 7:10 PM, Jonathan Hull <jh...@gbis.com> wrote: > I have a technical question on this: > > Instead of parsing these into identifiers & operators, would it be possible > to parse these into 3 categories: Identifiers, Operators, and Ambiguous? > > The ambiguous category would be disallowed for the moment, as you say. But > since they are rarely used, maybe we can allow a declaration (similar to how > we define operators) that effectively pulls it into one of the other > categories (not in terms of tokenization, but in terms of how it can be used > in Swift).
This is commonly requested, but the third category isn’t practical. Swift statically partitions characters between identifiers and operators to make it possible to parse a Swift source file without parsing all of its dependencies. If you could have directives that change this, it would be difficult or perhaps impossible to parse a file that used these characters without parsing/reading the transitive closure of dependent modules. This is important for compile speed and some tooling, and is an area that C gets wrong - its grammar requires all headers to be parsed in order to distinguish between type names and normal identifiers. -Chris _______________________________________________ swift-evolution mailing list swift-evolution@swift.org https://lists.swift.org/mailman/listinfo/swift-evolution
