{-# LANGUAGE PackageImports, BangPatterns, QuasiQuotes, PatternGuards #-}
{-# OPTIONS -Wall -fno-warn-missing-signatures -fno-warn-incomplete-patterns #-}

module Solver 
        ( Image
        , gradientX
        , gradientY )
where
import Data.Array.Repa                  as R
import Data.Array.Repa.Stencil          as R
import Data.Array.Repa.Stencil.Dim2     as R

type Image      = Array U DIM2 Float

gradientX :: Monad m => Image -> m Image
gradientX img
        = computeP
        $ forStencil2 (BoundConst 0) img
          [stencil2|    -1  0  1
                        -2  0  2
                        -1  0  1 |]
{-# NOINLINE gradientX #-}


gradientY :: Monad m => Image -> m Image
gradientY img
        = computeP
        $ forStencil2 (BoundConst 0) img
          [stencil2|     1  2  1
                         0  0  0
                        -1 -2 -1 |] 
{-# NOINLINE gradientY #-}