Mapped8
constructor(parentA: DeferredValue<A>, parentB: DeferredValue<B>, parentC: DeferredValue<C>, parentD: DeferredValue<D>, parentE: DeferredValue<E>, parentF: DeferredValue<F>, parentG: DeferredValue<G>, parentH: DeferredValue<H>, transform: (A, B, C, D, E, F, G, H) -> T)