miniblog.

I'm having fun writing a simple type checker, but I'm learning firsthand why syntax-directed checking doesn't work. It prevents inference. My checker catches real bugs, but it can't handle cases like this: [1, 2].map(fun(x) { x + 1; }) I think I need bidirectional checking.

Really cute approach to reporting type errors: when there's a type error, show an example of a runtime error that the type check has prevented! Data-Driven Techniques for Type Error Diagnosis https://escholarship.org/uc/item/59s4h4pv

I'm a huge fan of Swift's 'Error Handling Rationale' design document: https://github.com/swiftlang/swift/blob/9315673c003875158852579bd1f33480cdec5461/docs/ErrorHandlingRationale.md#fundamentals It carefully defines terminology and compares with other languages, so you can understand Swift's position and preference in the design space.