[math-fun] types in languages

Well, what is wrong with just declaring the types of all the variables, dammit? Sure, maybe many of the types could be "deduced" without you declaring them, but I think forcing you to declare them clarifies thinking and makes the code easier to understand when reading it, at little cost, so this is a feature not a bug. It is like the "cast of characters" at the beginning of the script of a play. Sure, you could deduce it. Hah. And if it is really turing undecidable, then at least sometimes, it is damned hard to make the deductions, proving the necessity of My Way.