Re: Changes to Typeable

Well, I think there is a general consensus that the existing manual instances for Typeable are more of a liability than a feature, and were a necessary evil given the limitations of the previous system, so either ignoring them or making them an error would make a lot of sense. -Edward On Thu, Oct 4, 2012 at 3:42 PM, Dominique Devriese < dominique.devriese@cs.kuleuven.be> wrote:

Small note while I happen to be reading the list:

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Plan A (easy): make GHC derive Typeable for everything, deprecate all uses of 'deriving Typeable'. Small downside: some

2012/10/3 Simon Peyton-Jones : programs

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that are currently rejected will be accepted.

Does this imply forbidding user-written instances of Typeable? If yes, then I guess some currently accepted programs would also be rejected (those with manual instances)? If not, then wouldn't there be duplicate instances? Or would manual instances somehow take priority? Or be ignored?

Dominique

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