In article <[EMAIL PROTECTED]>,
Brandon Michael Moore <[EMAIL PROTECTED]> wrote:
> Actually, I'm surprised someone else has a use for this. I wanted
> circular instances for playing with the paper "Recursion Schemes from
> Comonads". What are you trying to do?
It's for HScheme. The Object type has a pluggable reference type, so
that both IO-based and pure functional Scheme variants are possible.
The general idea is something like this:
data Object ref = NilObject |
PairObject (ref (Object ref)) (ref Object ref));
instance (Eq (ref (Object ref))) => Eq (Object ref) where
etc.
newtype Constant a = MkConstant a deriving Eq;
equalConstant :: Object Constant;
equalConstant = (==);
equalIORef :: Object IORef;
equalIORef = (==);
--
Ashley Yakeley, Seattle WA
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