[zsyllepsis]

> Making the red go away is important because the red indicates a problem! This is a lot easier than other ways of discovering the error. Why would you want to discover the error later?

I don't think that's what the parent to your comment is arguing. They are arguing that "making the red go away" isn't the goal, rather that correctness is, and that it's easy to conflate the too when you focus too much on the "red" part, and don't pay attention to the "correct" part.

Worded another way, the mantra of "if it compiles it works" can lead to a dangerous false sense of security if you don't understand the limitations of your type system and what parts of your program is may or may not cover completely.

[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.

[drekipus]

I have this all the time at work.

We have large python codebase, all sorts of linters and checks.

Still have developers do something like:

    # we have a list of things
    # but we only need one
    try:
        a_thing = things[0]
    except IndexError:
        pass
    assert isinstance(a_thing, Thing)

Sure maybe it's a junior thing. But it still happens, and the typing doesn't save us. I don't know how to tell juniors to stop doing this

[jpc0]

While discussing code review, howabout shooting whoever wrote that comment.

Why is there an assert? Python case a cast function if you really wanted to force the typechecker to see a_thing as Thing but (and I'm sure this is the point you are making) you are likely hiding a prolem.

[packetlost]

In code review, explain what can go wrong and offer suggestions for how to write it such that it doesn't have those problems?