Changes to Typeable

Oren Ben-Kiki haskell-oren at
Wed Oct 3 15:18:17 CEST 2012

Plan A does seem better.

Speaking of making changes to Typeable, is there a chance of
connecting/converting between Data.Typeable.TypeRep and

Oren Ben-Kiki

On Wed, Oct 3, 2012 at 3:03 PM, Edward Kmett <ekmett at> wrote:

> I'm definitely in favor of Plan A.
> -Edward
> On Wed, Oct 3, 2012 at 8:01 AM, Simon Peyton-Jones <simonpj at>wrote:
>> * If we do make Typeable instances by default, there are two paths
>>    Plan A (easy): make GHC derive Typeable for everything, deprecate
>>             all uses of 'deriving Typeable'.  Small downside: some
>> programs
>>             that are currently rejected will be accepted.
>>    Plan B (tiresome): have AutoDeriveTypable as an extension.  That
>>            means maintaining the massive instance table.
>>    Personally I vote for Plan A.   It's easier and more efficient to
>> implement,
>>    and the upside of Plan B is modest in the extreme.
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