Is it possible to write something like:
data SomeData = SomeValue | (Integral a) => SomeConstructor a
And how exactly would one write this?
Is it possible to write something like: data SomeData = SomeValue | (Integral a)
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Is it possible to write something like:
data SomeData = SomeValue | (Integral a) => SomeConstructor a
And how exactly would one write this?
This is similar to Daniel Pratt’s answer, but the more typical approach is to leave off the type constraints on your data definition, like this:
Instead, you should put the
(Integral a)constraint on any functions that require it, which you’d have to do even if you added the constraint to the data definition too. Putting the constraint on the data definition buys you nothing, but forces you to carry around the constraint on all uses ofSomeData, even those that don’t care whatais at all. See Chapter 10 of Real World Haskell for more.