Changes to Typeable

Roman Leshchinskiy rl at
Mon Feb 13 00:23:49 CET 2012

On 12/02/2012, at 03:21, Iavor Diatchki wrote:

> PS: I wouldn't worry too much about breaking existing code, as long as
> derived Typeable instances continue to work---I never provide custom
> ones and, in fact, I think that GHC should no allow them or, at least,
> give a stern warning when it sees one.

There is no easy way to have derived Typeable instances for data families. Standalone deriving works, but only since 7.2 and only like this:

data family T a
deriving instance Typeable1 T

Presumably, this should be Typeable rather than Typeable1 with the new design.


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