Can we implement a faster version of alongside?

[ekmett]

We switched to a final encoding of Bazaar because it made cloning dramatically faster. Would a final encoding of Context have a similar performance impact? e.g.

newtype Store c d a = Store { runStore :: forall f. Functor f => (c -> f d) -> f a }

This might also speed up a number of Control.Lens.Plated combinators.

[ekmett]

Benchmarks seem to bear out that the current version is the fastest reasonable implementation. Closing this out.