[troupo]

I don't think any of that has to do anything with static analysis deficiencies. The analysis is the same. What Swift requires is for the user to manually help the compiler with a rather verbose and otherwise unnecessary construct.

Type narrowing is not a new idea

[saagarjha]

It’s not a new idea, but I don’t think it’s a good idea. That’s just it. Swift has a construct to do the equivalent and it’s fewer characters to boot when compared to Dart when you’re going from an optional to non-optional type.

[troupo]

But that's exactly what Swift does: it narrows the types. To do that, it uses a separate construct that only exists to make the parser ever so slightly simpler.

[saagarjha]

Yes and I think having a separate construct rather than using another one and imbibing it with new meaning is more elegant