ProfunctorRecordTypeable.versionSwitch for version control

[clinuxrulz]

public interface ProfunctorRecordTypeable<F_> extends Profunctor<F_> {
    <A,B,V> __<__<F_,P2<A,V>>,P2<B,V>> versionSwitch(PRecordTypeable<V,V> version, F<V,PRecordTypeable<A,B>> switchFn);
    .
    .
    .
}

This allows handling JSON/XML files with version numbers. On loading you can read the version number field then switch to another loader based on the version.

[clinuxrulz]

The type signature works for Load/Save

    @Override
    default <A, B, V> __<__<PLoadSave.Mu, P2<A, V>>, P2<B, V>> versionSwitch(PRecordTypeable<V, V> version, F<V, PRecordTypeable<A, B>> switchFn) {
        PLoadSave<V,V> versionLoadSave = PLoadSave.narrow(version.run(instance));
        return new PLoadSave<P2<A,V>,P2<B,V>>() {
            @Override
            public <E, M> __<M, P2<B, V>> load(DataSourceEffects2<E, M> eff) {
                return eff.monad.bind(
                    versionLoadSave.load(eff),
                    (V v) ->
                        eff.monad.fmap(
                            (B b) -> P.p(b, v),
                            PLoadSave.narrow(switchFn.f(v).run(instance)).load(eff)
                        )
                );
            }
            @Override
            public <E, M> __<M, Unit> save(DataSinkEffects2<E, M> eff, P2<A, V> av) {
                return eff.monad.seqRight(
                    versionLoadSave.save(eff, av._2()),
                    PLoadSave.narrow(switchFn.f(av._2()).run(instance)).save(eff, av._1())
                );
            }
        };
    }