showScreen :: Screen -> String
showScreen screen = unlines [showRow r | r <- [minRow..maxRow]]
where ((minRow, minCol), (maxRow, maxCol)) = bounds screen
- showCell True = '#'
- showCell False = '.'
+ showCell True = '*'
+ showCell False = ' '
showRow r = [showCell (screen!(r, c)) | c <- [minCol..maxCol]]
countLights :: Screen -> Int