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"huge unit testing burden necessary"

Why do you consider unit testing a burden? I find unit tests the best way to formalize specifications before even starting to write code.

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Unit testing is a burden because (a) a programmer needs to think of the cases that must be tested, (b) a programmer needs to actually write them, (c) they can only act as a safety net. When possible, it's very advantageous to encode your invariants into the type system. Yaron Minsky gives a good example in his Effective ML talk[1] about how you can take a common data structure and refactor it in such a way that the type system prevents you from ever creating an illegal state. (Note: this doesn't absolve statically typed languages from having suites of tests, it just allows them to remove large swaths of those tests if they can be enforced by the type system.)

[1] https://youtu.be/DM2hEBwEWPc?t=1085

Type systems are a burden because (a) a programmer needs to think of the types he or she should design, (b) a programmer needs to actually utilize those types to write his or her program, (c) they can only act as a safety net.

As always, there is a tradeoff. Like the gp mentioned, type systems allow you elliminate much unit test code that would otherwise be required.

Personally, I do love me a type system. Even if you have to think harder about how to architect your code, I think this kind of thinking is required for software to be good.

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