> That is the meat of why Haskell is so great. I've never so reckless refactored code as much as I do in Haskell, I just wait for the compiler to tell me what I

> That is the meat of why Haskell is so great. I've never so reckless refactored code as much as I do in Haskell, I just wait for the compiler to tell me what I missed and go back and fix it up. I'd never do that in C, C++, Java, etc; it'd be suicide. I work on Java projects and do big re-factorings using IntelliJ, relying on the compiler. So this is a bit project-dependent. Java chooses two wrong defaults - nullability by default, and mutability by default. If your project consciously chooses to not opt into these defaults, from my experience, you can use javac to guide you in fearlessly making large refactorings.