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And this is why nullable data types are important!

• Filligree 10y ago
  Nullable types are fine. The key is to make them explicitly nullable, so that programmers are allowed to use non-nullable types as well. Both need to be permitted. Ideally by way of sum types, but Kotlin's approach should be okay.
  • sanderjd 10y ago
    Why do you need both? Are there use cases for null that are not covered by a (non-nullable) type with present and absent variants?
    • clappski 10y ago
      I think the distinction between nullable types and the non-nullable types you speak of is fairly narrow, you've just made it type safe (which isn't a bad thing!).
      • sanderjd 10y ago
        I don't necessarily disagree, what I don't understand is the parent comment's use of the word "need" in "Both need to be permitted". It makes me think there is something nullable types can do that non-nullable types can't do, and I'm just not sure what that is. Something like "it is fine to permit both" would make sense to me. I guess maybe it's because in a language with no value types (like anything on the jvm), using Optionals everywhere requires a lot more objects to be allocated, so in allocation-sensitive code it might make more sense to use nulls instead.