Another Conway's Game of Life in Haskell

Question

Curious what people think about this implementation of Conway's Game of Life in Haskell.

{-# LANGUAGE QuasiQuotes #-}
module Test.Conway (
 conwayCalculateAge,
 conwayStep,
 conwayMakeRandom,
 conwayMakeRandomIO,
 conwayMakeEmpty
 ) where
import Data.Array.Repa
import Data.Array.Repa.Stencil
import Data.Array.Repa.Stencil.Dim2
import Data.Functor.Identity
import System.Random
conwayNeighborsStencil :: Stencil DIM2 Int
conwayNeighborsStencil =
 [stencil2| 1 1 1
 1 0 1
 1 1 1 |]
conwayStep :: Array U DIM2 Int -> Array U DIM2 Int
conwayStep r =
 runIdentity . computeP . szipWith rules r . -- Apply rules
 mapStencil2 (BoundConst 0) conwayNeighborsStencil $ r -- Find # neigbors
 where
 rules 1 2 = 1 -- Alive and has two neighbours
 rules _ 3 = 1 -- Alive or dead and has three neighbours
 rules _ _ = 0 -- All others are dead
conwayMakeRandom :: RandomGen g => g -> DIM2 -> Array U DIM2 Int
conwayMakeRandom g sh =
 fromListUnboxed sh $ take (size sh) $ randomRs (0, 1) g

Naturally, conwayMakeRandom creates the initial grid and conwayStep advances the evolution a grid.

Answer 1

That's a nice use of stencil2 and Repa. All in all there isn't much to review, it follows a common approach on Conway's Game of Life with Repa. No type signatures are missing, but with Repa it's more or less mandatory to add them.

Well done. But the next time, consider adding all your code, conwayCalculateAge and conwayMakeEmpty were probably interesting (I suspect conwayMakeRandomIO to be the same as conwayMakeRandom but using randomRIOs = randomRs (0, 1) <$> newStdGen).