Can I ask a question about the use of 'null' and 'Maybe' types?

I have a question that I was going to post on Software Engineering, but I suddenly stumbled upon this site, and now I'm wondering if the question would be on-topic here.

There's a draft available here, but here's a summary:

I'm now wondering if it makes sense to have both the concept of null and Maybe, to represent unknown and nothing respectively. Is this the three-valued logic I read about, or does it have another name? Or is the intended way to nest a Maybe in a Maybe?

Looking at your questions, they all seem to be a lot more theoretical than my question, so I think it's off-topic, but figured it couldn't hurt to ask.

• This seems to be on topic here, I'm just not sure about which tags to use, maybe programming-languages + some more specific tag. Dec 30 '16 at 2:35
• This is not at all an answer to your question, but note that Maybe is a type constructor, not a type unto itself; it is sometimes important to understand this difference. (In Haskell-speak, its kind is * -> *, not just *.) Jan 4 '17 at 4:47
• @wchargin Thanks for your input. The question was posted here fyi :) Jan 4 '17 at 8:40
• That question turned out to prompt very interesting answers, thanks!
– Raphael Mod
Jan 4 '17 at 9:02