People keep arguing for array covariance as if soundness and developer ergonomics were in conflict, but upgrading your type system from a laptop keyboard to som

People keep arguing for array covariance as if soundness and developer ergonomics were in conflict, but upgrading your type system from a laptop keyboard to some infamously-sound Cherry MX blues shows you indeed can have both. With the amount of high-quality keyboard manufacturers these days, though, and the support for variance in preferred type parameters—do you need backlighting? Mac keys?—I do not blame people for asserting the problem of picking one is undecidable.