Representableのinstance例: Vector
#WIP
https://qiita.com/lotz/items/5a1a05c0dae1133a5f44#vector-n-a
https://www.works-hub.com/learn/representable-functors-by-example-6c5c0
code:hs
import qualified Data.Vector.Sized as V
instance KnownNat n => Representable (V.Vector n) where
type Log (V.Vector n) = Finite n
index = V.index
positions = V.generate id