[spankalee]

> the mantra of "if it compiles it works"

Very few people have this mantra, much less without qualification. That's more of a ML or Haskell kind of point of view, and even then it's known to not be a guarantee. A type Int -> Int -> Int isn't going to enforce that you implement multiplication correctly, instead of add or just 0.

"I refactored, fixed type errors, and it just worked!" is a thing I see a lot, but from people who just experienced it, because it happens a lot. It's a good thing.