Equality constraint type mismatch

Simon Peyton-Jones simonpj at microsoft.com
Tue Mar 9 03:03:35 EST 2010

| type family T a :: *
| my_id :: f a -> f a; my_id = id
| x :: T a -> T a; x = my_id
| IMHO, this was not clear from the documentation or from the error
| message (It certainly _looks_ like "T a" should match "f a"...).
| Thanks for the explanation.

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Please edit it to improve the clarity, or add a whole new sub-section if you think that would be clearer.  It's a wiki.


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