The venerable Uncle Bob makes the case for dynamic typing and TDD. Be sure to read the entire article to get a quick history lesson in computer languages.

The pendulum is quickly swinging towards dynamic typing. Programmers are leaving the statically typed languages like C++, Java, and C# in favor of the dynamically typed languages like Ruby and Python. And yet, the new languages that are appearing, languages like go and swift appear to be reasserting static typing? So is the stage for the next battle being set? How will this all end? My own prediction is that TDD is the deciding factor. You don't need static type checking if you have 100% unit test coverage. And, as we have repeatedly seen, unit test coverage close to 100% can, and is, being achieved. What's more, the benefits of that achievement are enormous.

http://blog.cleancoder.com/uncle-bob/2016/05/01/TypeWars.html