[pclowes]

I like this approach, there are often calls for increased testing on big systems and what they really mean is increased rigor. Don't waste time testing what you can move into the compiler.

It is always great when something is so elegantly typed that I struggle to think of how to write a failing test.

What drives me nuts is when there are testing left around basically testing the compiler that never were “red” then “greened” makes me wonder if there is some subtle edge case I am missing.

[eyelidlessness]

As you move more testing responsibilities to the compiler, it can be valuable to test the compiler’s responsibilities for those invariants though. Otherwise it can be very hard to notice when something previously guaranteed statically ceases to be.