open-witness-0.3.1: Data/OpenWitness/Dynamic.hs

-- | This is an approximate re-implementation of "Data.Dynamic" using open witnesses.
module Data.OpenWitness.Dynamic where
{
{-
    import Data.Witness;
    import Data.OpenWitness.OpenRep;
    import Data.OpenWitness.Typeable;

    -- * The @Dynamic@ type
    ;

    type Dynamic = Any OpenRep;

    -- * Converting to and from @Dynamic@
    ;

    toDyn :: Typeable a => a -> Dynamic;
    toDyn = MkAny rep;

    fromDyn :: Typeable a => Dynamic -> a -> a;
    fromDyn dyn def = case fromDynamic dyn of
    {
        Just a -> a;
        _ -> def;
    };

    fromDynamic :: forall a. Typeable a => Dynamic -> Maybe a;
    fromDynamic (MkAny uq a) = do
    {
        MkEqualType <- testEquality uq (rep :: OpenRep a);
        return a;
    };

    -- * Applying functions of dynamic type
    ;

    dynApply :: Dynamic -> Dynamic -> Maybe Dynamic;
    dynApply (MkAny (ApplyOpenRep (ApplyOpenRep1 repFn' rx') ry) f) (MkAny rx x) = do
    {
        MkEqualType <- matchOpenRep2 repFn' (rep2 :: OpenRep2 (->));
        MkEqualType <- testEquality rx' rx;
        return (MkAny ry (f x));
    };
    dynApply _ _ = Nothing;

    dynApp :: Dynamic -> Dynamic -> Dynamic;
    dynApp a b = case (dynApply a b) of
    {
        Just d -> d;
        _ -> error "Type error in dynamic application.\nCan't apply function to argument";
    };

    dynTypeRep :: Dynamic -> TypeRep;
    dynTypeRep (MkAny r _) = MkAnyWitness r;
-}
}