DESIGN.md

-- New design: -- Binder arity info body -- info must be indexable

-- info -> rec/non-rec -- Lens from info to (Seq e)

class WithArity i where asArity :: Int -> i

class WithArity (Ix n) => WithIndex n where type Ix n type Res n lookupIx :: n -> Ix n -> Maybe (Res n) rebuildIx :: (Ix n -> Res n) -> n -> n