instance Typeable (Re: How do I create dynamic exceptions)

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data MyException = MkExc Int String

... but now it seems I have to install this as an instance of Typeable, and I don't see how to do that.

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instance Typeable MyException where typeOf ? = ?

import Data.Dynamic myExceptionTc = mkTyCon "MyException" instance Typeable MyExceptionBasicSpec where typeOf _ = mkAppTy myExceptionTc [] The above should work, but I wonder when it is possible to simply derive Typeable? Cheers Christian