Re: [Haskell-cafe] Dynamic types through unsafeCoerce

13 Dec 2006

      On 12/13/06, Taral  wrote:
...
On 12/13/06, Alfonso Acosta  wrote:
...
deactivate             :: Maybe(hd -> IO ()),
According to the spec, NULL here means no-op. So instead of using
Maybe, just set deactivate = \_ -> return () if you see NULL.
I considered this solution as well, but is not really acceptable cause
the function would be called anyway (which would harm performance).

Furthermore is not sematically correct as externally the descriptor
would be viewed as having a deactivate.