Day 14 but kind of shitty

day14/Commons.hs

@@ -0,0 +1,37 @@
+module Commons where
+
+import GHC.IO.Handle (isEOF)
+import Data.Array (Array, listArray, bounds, (!), (//))
+
+
+data Tile = Empty | Round | Square deriving (Eq, Show)
+type Platform = Array (Int, Int) Tile
+
+
+parseLine :: String -> [Tile]
+parseLine [] = []
+parseLine ('O': t) = Round: parseLine t
+parseLine ('#': t) = Square: parseLine t
+parseLine ('.': t) = Empty: parseLine t
+
+parsePlatform :: IO [[Tile]]
+parsePlatform = do done <- isEOF
+                   if done
+                      then return []
+                      else do line <- getLine
+                              let platformLine = parseLine line
+                              platform <- parsePlatform
+                              return (platformLine: platform)
+
+parse :: IO Platform
+parse = do platform <- parsePlatform
+           return (listArray ((1, 1), (length platform, length $ head platform)) $ concat platform)
+
+
+tilt :: (Int, Int) -> [(Int, Int)] -> Platform -> Platform
+tilt _ [] platform = platform
+tilt (yI, xI) ((y, x): t) platform
+  | let (y2, x2) = (y + yI, x + xI)
+    in y2 > 0 && y2 <= fst (snd $ bounds platform) && x2 > 0 && x2 <= snd (snd $ bounds platform)
+       && platform ! (y2, x2) == Empty = tilt (yI, xI) ((y + yI, x + xI): t) $ platform // [((y, x), Empty)]
+  | otherwise                          = tilt (yI, xI) t $ platform // [((y, x), Round)]