This is great, and I'm developing a static type system for my programming language (for board games), and I've messed up the type system so many times. The cha

This is great, and I'm developing a static type system for my programming language (for board games), and I've messed up the type system so many times. The challenge beyond the math is then making the error messages useful, and also being able to make progress beyond the first error in a useful way.