Static types mean that you never have to write behavioral tests. If you're writing behavior tests, you're just writing a very verbose subset of the same guarant

Static types mean that you never have to write behavioral tests. If you're writing behavior tests, you're just writing a very verbose subset of the same guarantees that types offer instantly. Moreover, running code snippets in a repl only help if your codebase is small and you're designing it mostly alone. 3 months later, when someone needs to add a new feature and they call your function with incorrect assumptions (sending a dictionary with missing keys for example) then you'll have something that can work in the happy path, but doesn't work around the edge cases. I've seen behavioral tests try to address this, but again, that's just an inferior form of typing.