[eru]

> This kind of reasoning is generally accepted when talking about implicitly nullable types vs explicitly nullable types (optional types), but somehow in this context people are more stubborn.

Not sure that's the same? Haskell has no implicitly nullable types. Everything not explicitly marked as optional is non-nullable.

But still, if your algorithm at hand can treat nulls the same as non-nulls, it's a good idea to do so. (Eg in a sorting algorithm where you just feed the elements to the user supplied comparison function, and let that function handle comparing of optional elements.)