import Clash.Prelude

type Matrix a rows cols = Vec rows (Vec cols a)

getNthCol
  :: (KnownNat rows, KnownNat cols)
  => Matrix a rows cols -- matrix
  -> Int                -- n
  -> Vec rows a         -- nth column of matrix
getNthCol mat n = map (\rw -> rw !! n) mat

transpRow
  :: KnownNat n
  => Vec n a
  -> Matrix a n 1
transpRow Nil = Nil
transpRow v = ((head v) :> Nil) :> (transpRow $ tail v)
--transpRow (x :> xs) = (x :> Nil) :> (transpRow xs)


dotProduct
  :: (KnownNat n, Num a)
  => Vec n a
  -> Vec n a
  -> a
dotProduct p q
  = foldr (\x acc -> acc+x) 0
  $ map (\x -> (fst x)*(snd x))
  $ zipWith (,) p q

-- matProd p q

eg1
  = (0 :> 1 :> 2 :> Nil) :>
    (3 :> 4 :> 5 :> Nil) :>
    Nil
-- λ> getNthCol eg1 0
-- 0 :> 3 :> Nil