--- Writeup at https://work.njae.me.uk/2021/12/04/advent-of-code-2021-day-4/
+-- Writeup at https://work.njae.me.uk/2021/12/05/advent-of-code-2021-day-5/
import Data.Text ()
import qualified Data.Text.IO as TIO
dy = signum (y1 - y0)
addLines :: Grid -> [[Point]] -> Grid
--- addLines diagram expandedLines = foldr insertLine diagram expandedLines
addLines = foldr insertLine
where insertPoint p d = M.insertWith (+) p 1 d
insertLine l d = foldr insertPoint d l