On Monday, 18 March 2024 at 22:36:21 UTC, Walter Bright wrote: > Another issue with this approach is as soon as you pass `a` to > another function, `bar(a)`, the body of `bar` doesn't know if > `a` is null or not. Hmm... why? If type of `a` is non-nullable `A` compiler know that in bode of `bar(A a)` argument `a` is never `null`.