> It also means that when you change a function signature, the compiler can't tell you all the call sites you need to fix. You have to find them through testing

> It also means that when you change a function signature, the compiler can't tell you all the call sites you need to fix. You have to find them through testing. This is a large barrier to aggressive refactoring. This is a problem inherit to every dynamic language. You sacrifice brain-dead refactoring for improvements and tradeoffs elsewhere. Not to mention that modern IDEs and tools like Rope [1] can definitely help. [1] http://rope.sourceforge.net/ http://rope.sourceforge.net/