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Your brain is going to explode like mine did when you learn about Option types[1]. [1] https://en.m.wikipedia.org/wiki/Option_type https://en.m.wikipedia.org/w

• ericpauley 7y ago
  This doesn't really solve GP's problem, as the Nothing type is generally still equal to itself. Certainly useful for general purpose programming languages, though.
  • Smaug123 7y ago
    The problem is really that you're using the wrong equality type here. You get the right semantics if you use `= : A -> A -> Bool` and then apply it to a `Maybe A` and a `Maybe A` by lifting it: you end up with `Nothing` if either input was `Nothing`, and `Just answer` if both were known.