What cheng said, but we could also make sure that the syntax for modular implicits plays very nicely with the rest of the grammar. With Reason we can rethink the grammar holistically instead of having to find room in it for new features. The hard part is in the actualy implementation of Modular Implicits, but that's currently being handled by skilled professionals and Reason will be able to use them.
Yes, I'd describe it as being "non-invasive". It means we get the benefit of literally every feature implemented in the core of the language (multicore, F-lambda, modular implicits, ppx attributes), but can decouple the process of deliberating over how this is presented to the user, and (not to beat a dead horse) but we don't even have to worry about getting it right on the first try! Now that I've embraced this as the new "normal" way, I couldn't imagine having to design a syntax and stress over having to determining the exact permanent concrete syntax that needs to live virtually forever without knowing which other language features will be added later.
