…tion expects/returns, is very useful. Instead of having to go to look into the codebase or the docs you simply look at the suggestions and most of the times you should be able to remember the info you need to go on.
It depends. On some projects, I’m dealing with hundreds of API calls from dozens of libraries. And many of these I seldom use, so it’s unlikely I’ve committed them to memory.
I’m not saying static typing isn’t useful. I’m saying it’s not a slam-dunk over dynamic typing. That’s why I don’t choose a language on the basis of data typing. I’m happy to use either Go or Smalltalk, Java or Python, Haskell or Scheme. Choose what is appropriate for the job.