Data.Massiv.Array.Sized.One.hs

{-# LANGUAGE DataKinds, DeriveFunctor, GADTs, KindSignatures,
  ScopedTypeVariables, TemplateHaskell, TypeFamilies,
  TypeApplications #-}

module Data.Massiv.Array.Sized.One where

import CoercibleUtils
import Data.Coerce
import Data.Finite
import Data.Foldable
import Data.Kind
import Data.Proxy
import Data.Singletons
import Data.Singletons.TH
import Data.Singletons.TypeLits
import Numeric

import qualified Data.Massiv.Array as MA

data Strategy
  = Seq
  | Par

genSingletons [''Strategy]

newtype DelayArray (s :: Strategy) (n :: Nat) (a :: Type) =
  DelayArray (MA.Array MA.D MA.Ix1 a)
  deriving (Eq, Ord, Show, Functor)

-- Given that 's' can _only_ be of kind Strategy, why do I need the SingI s constraint here?
-- Shouldn't it know that it must have a SingI, or am I missing something?
instance (SingI s, KnownNat n) => Applicative (DelayArray s n) where
  pure = make . const
  (<*>) = coerce (MA.zipWith ($))