[valenterry]

> I don't get this argument.

Maybe it's because you focus on typescript here. But typescript is in a position that other languages are not: it has to make things work within an existing ecosystem, in particular with an untyped language. Under these constraints, flow typing might be the best solution. But that doesn't mean it's generally "at least as good as pattern-matching/switch-blocks".

Btw, pattern matching and switch-blocks are very different things - maybe it make it easier for you to understand to dive into a language that has native pattern matching and no switch-blocks at all because from what you write it seems to me that you have not been exposed to pattern matching much yet.