QuackingTheQ
1. Running the whole testing framework to determine if you implemented an interface is a high overhead when you're developing
2. You have a lot of tests to write to really check every error. Perhaps a package which defines an interface could provide a tester for this purpose
3. Interfaces should be attached to the types, and that should be sufficient for verifying the interface
I would settle for something like checking for the implementation of methods a la BinaryTraits.jl over what we have now, which is nothing. A huge step would be documentation and automated testing that proper interface methods are implemented, not even verifying if they're "correct". This drastically reduces the surface area you need to write and check to confirm compatibility with outside code.
This simple interface specification does produce design issues of its own, but correctness is much easier to handle if you know what needs to be correct in the first place.
This doesn't catch mathematical bugs, but those crop up everywhere. Instead, knowing what the interfaces must be specified so you can trust your implementation is crucial, and being able to know when it is invalidated is invaluable.
I've had a few awful bugs involving some of the larger projects in this language, but a proper interface/trait system would simplify things exponentially. There are some coding style things that need to be changed to address this, like using `eachindex` instead of `1:length(A)` for array iteration as the example in the article points out. However, these should be one-off lessons to learn, and a good code linter should be able to catch potential errors like this.
Between a good code linter (or some static analysis, I'm pulling for JET.jl) and a formal interface spec, I really think most of Julia's development-side issues could be quelled.