[Haskell-beginners] Structural restrictions in type constructor

[Matt Williams]

Dear All,

I wonder if/ how this is possible?

I have a constructor which takes 2 pairs of type t).

However, I want to ensure that the pairs are matched:

MyP = MyP (t, t) (t, t)

But where the first pair contains the same elements as the second, but
reversed in order.

Any help much appreciated.

BW,
Matt
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