Our journey to type checking 4M lines of Python
The worst, buggiest, least maintainable code I've ever dealt with was a 500ish line (heavily tested!) untyped Python file at my last job. Caused more trouble than all the Java and C++ and Go combined.<p>My personal experience with compile time type checking is that the benefits kick in for a single developer project within a week, and for a multi-developer project immediately.