I want different things at different times. When I'm first exploring a problem space or figuring out an approach or fooling around in a REPL, dynamic typing is

I want different things at different times. When I'm first exploring a problem space or figuring out an approach or fooling around in a REPL, dynamic typing is great. In those circumstances, the ability to quickly test (and reject!) ideas is critical, and I don't usually find static typing worth the friction. On the flip side, when I'm working on something longer lived or mission critical, it's important to set the maintenance brigade up for success. That means, among other things, useful doc strings; detailed and informative design notes; and type declarations with the right level of specificity. Of course, the coin has a thin edge where the situation is a bit of heads and a bit of tails. Count me a fan of gradual typing.