Changes to Typeable
komadori at gekkou.co.uk
Wed Oct 3 22:26:37 CEST 2012
On 03/10/12 14:20, Edward Kmett wrote:
> I don't think anyone has proposed weakening parametricity in this way.
I don't think so either, but is there any reason it shouldn't be done?
If you give every type a Typeable instance automatically, then it's not
effective as a constraint. The compiler would be free to either still
use the type-class mechanism behind the scenes or "simply" replace it
typeOf :: a -> TypeRep
typeOf = rtsInternalGetTypeOf
Simon's comment that it "would save tons of lookup in the massive
Typeable-instance table" seemed to me to imply that there was some kind
of optimisation you could make if Typeable wasn't really a type-class
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