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.

  • 3
    $\begingroup$ This seems to be on topic here, I'm just not sure about which tags to use, maybe programming-languages + some more specific tag. $\endgroup$
    – Aristu
    Commented Dec 30, 2016 at 2:35
  • $\begingroup$ 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 *.) $\endgroup$
    – wchargin
    Commented Jan 4, 2017 at 4:47
  • $\begingroup$ @wchargin Thanks for your input. The question was posted here fyi :) $\endgroup$
    – Stijn
    Commented Jan 4, 2017 at 8:40
  • 1
    $\begingroup$ That question turned out to prompt very interesting answers, thanks! $\endgroup$
    – Raphael
    Commented Jan 4, 2017 at 9:02

1 Answer 1


We do have the and tags. As long as your questions fall into these categories and are (mostly) language-agnostic they are very welcome!


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