*sigh*. I wonder why comments like this in Dynamic.lhs
"Provided the implementor of other @Typeable@ instances
takes care of making all the @TyCon@s CAFs (toplevel constants),
this will work."
...donīt get written in bold, bright and friendly letters across the
(HTML-)documentation...
Of course afterwards it seems straight forward to skim *all* of the
library source-file,
but I suggest putting this note near the *top* of Dynamic.lhs ;)
If you donīt create a function like
> instance Typeable Msg where
> typeOf _ = mkAppTy msgTc []
> msgTc :: TyCon
> msgTc = mkTyCon "Msg"
but simply use
> instance Typeable Msg where
> typeOf _ = mkAppTy (mkTyCon "Msg") []
you can search for hours why "fromDynamic" wonīt work.
Volker
--
"I came out of it dead broke, without a house, without anything, except
a
girlfriend and a knowledge of Unix." "Well, thatīs something. Normally
those
two are mutually exclusive." N. Stephenson, "Cryptonomicon"
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