Well there's also the fact that the types flow downward from the interface. Like the source of truth comes from your function parameter types that are always explicitly written. One thing that tripped me up writing OCaml is that you could have a mistake in your function that'd show up as a bug in a completely different location due to the inference algorithm. Like dumb example but say I have `foo` instead of `foo()` that changes the function return type to be a () -> int instead of int. You'll get the error when you use the function result instead of inside the function.