Rewrite with lenses?

[snarfed]

Granary does what's affectionately known as "shotgun parsing." Its translation logic is consistently mixed with .get()s, conditionals, and similar handling for fields that can be optional, have multiple types, etc.

Lenses are one alternative. They separate normalization from translation so that translation can assume a static schema with many more guarantees and invariants.

In an alternate world, granary could be a lens engine and a set of lens transformations between formats. It'd probably be best to do it as a full rewrite, or even a separate project altogether. Worth a try sometime!