A possible solution to the nested Maybes issue

[nikita-volkov]

Have you considered having multiple definitions of null, one per the level of nesting? E.g.,

data Null1 = Null1
data Null2 = Null2
-- ...

-- Equivalent of `Nothing :: Maybe (Maybe Int)`
twoLevelMaybeNothing :: Maybe (Maybe Int)
twoLevelMaybeNothing = unsafeCoerce Null2

-- Equivalent of `Just Nothing :: Maybe (Maybe Int)`
twoLevelMaybeJustNothing :: Maybe (Maybe Int)
twoLevelMaybeJustNothing = unsafeCoerce Null1

Then the choice of the proper null could be determined through type-classes or reflection.