[Haskell-cafe] Implementation of "Dynamic" datatype

Simon Peyton-Jones simonpj at microsoft.com
Fri Mar 9 15:20:59 EST 2007

| I think
| data Dynamic where
|         Dynamic :: a -> TypeRep -> Dynamic
| would be better, as it would cache the TypeRep for fast equality, while
| the 'Typeable' version would perhaps have to go through a dictionary
| lookup to get at it.

But the dictionary would presumably contain a cached version, since the result is independent of the argument.  So I doubt this is a big issue in practice.


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