`NoneType`

[rolyp]

PurePy has a data type called NoneType (not sure if you can actually name it) with a single constructor, None. That's all fine and dandy but I think Fluid will be quite restrictive about this compared to Python, at least initially: in Python you can have a value whose (effective) type is NoneType | SomeOtherDataClass and still pattern-match on the value; not sure how we can support that easily in Fluid.

• Rename Unit to NoneType

[rolyp-claude-bot]

Fluid's existing Option type uses None as a constructor (alongside Some), so introducing NoneType requires rethinking Option. We don't have sum types, so the Python T | None idiom isn't directly available.

[rolyp-claude-bot]

Closed by #1536 (NoneType added with single None constructor; Option renamed to Maybe with Nothing/Just to free up the name).