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
Small note while I happen to be reading the list:
2012/10/3 Simon Peyton-Jones <simonpj@microsoft.com>:
> Plan A (easy): make GHC derive Typeable for everything, deprecateDoes this imply forbidding user-written instances of Typeable? If yes,
> all uses of 'deriving Typeable'. Small downside: some programs
> that are currently rejected will be accepted.
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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