I claim Rich Hickey is wrong about non-null arguments to functions (2020)
I feel like they are talking past each other, or at least talking about different things.<p>Hickey seems to be talking about breaking <i>the compiler</i>. That is, he is saying that changing the return signature from null|int to int should not break the compilation. In effect, this would create a warning a la &#x27;You are checking for null, but var x cannot be null&#x27;.<p>The author seems to be talking about breaking changes in the behaviour&#x2F;operation sense.<p>Those are different types of breaking.