[Haskell-cafe] Monad for binary tree data structure

[Maciej Marcin Piechotka]

> 2) One possibility is just have it being (Node x _ _) >>= f = f x
> 

It does not follow monad laws (right identity to be more precise):

(Node 1 (Node 2 Empty Empty) Empty) >>= return ≡
return 1 ≡
Node 1 Empty Empty
≠
(Node 1 (Node 2 Empty Empty) Empty)

Regards
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