There’s nothing wrong with static type checking, It’s generally good and will prevent certain kinds of problems with out the cost of unit tests. I’m all for static checking generally, not just for types.
My point was to point out the limitations. I might be wrong, but people seem to often ignore these limitations. This oversells the benefits and leads to frustrated people like the one whose comment I originally responded to.
99.5% is not nothing, but not something you can live with in most systems so you are probably going to need something more. Also, you are going to be a lot happier if the vast majority of those hundreds of lines in your cross-system call stack are completely agnostic to the types of your problem domain and you want to be careful to minimize the coupling between components living on different sides of the jumps you mention. You can do that, of course, with static types, but it takes more care and intentional design and you really need to acknowledge the issues before you can get it reasonably right.
