Another Conway's Game of Life in Haskell
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) &lt;$&gt; newStdGen).