If you've got a way to compile Ruby to JS that has tolerable arithmetic perf and doesn't do type analysis or generate a huge volume of code, I would definitely like to know more about it.
Yeah, that's kinda the point, you can do that and preserve Ruby semantics?
Let me note here that is a strawman indeed, Dart has frozen classes, Ruby is a bit different. In order to do something like that you should inline a ton of ternary operator to check if the method has been redefined on that particular object.
Something like:
(a._isNumber && !a._plusRedefined) ? a + 1 : a['$+'](1)
plus listening on new method definitions to set _plusRedefined.
It's definitively a trade off, readability will suffer.
Opal had optimized operators in the past (that assumed native operations on numbers), they could even be back in the near future. But what I see here is a comparison of two different language semantics. I agree that “compiling to JS is hard”, but I don't think that this demonstrates anything. What can be argued instead is that JS VMs could and should do that for us.