Improve some code

src/Day12.hs

@@ -1,10 +1,10 @@
+{-# OPTIONS_GHC -Wno-x-partial #-}
+
 module Day12 (day12_1) where
 
 import Data.Foldable (toList)
 import Data.Graph (Tree, Vertex, graphFromEdges, scc)
-import Data.List (uncons)
 import Data.List.Split (chunksOf)
-import Data.Maybe (fromJust)
 
 type Coords = (Int, Int)
 
@@ -16,12 +16,12 @@ getValue grid (i, j) = grid !! i !! j
 getEdges :: [[V]] -> Coords -> [Int]
 getEdges grid (i, j) =
   let value = fst $ grid !! i !! j
-      adjI = filter (\x -> fst x >= 0 && fst x < length grid && snd x >= 0 && snd x < length (fst . fromJust $ uncons grid)) [(i, j + 1), (i + 1, j), (i, j - 1), (i - 1, j)]
-   in [snd x | x <- map (getValue grid) adjI, (fst . fromJust $ uncons value) == (fst . fromJust $ uncons (fst x))]
+      adjI = filter (\x -> fst x >= 0 && fst x < length grid && snd x >= 0 && snd x < length (head grid)) [(i, j + 1), (i + 1, j), (i, j - 1), (i - 1, j)]
+   in [snd x | x <- map (getValue grid) adjI, head value == head (fst x)]
 
 listVertices :: [String] -> [[V]]
 listVertices grid =
-  let l = length $ fst . fromJust $ uncons grid
+  let l = length $ head grid
    in chunksOf l $ zip (map (: []) (concat grid)) [0 ..]
 
 calculatePerimeter :: (Vertex -> (String, Vertex, [Vertex])) -> Tree Vertex -> Int
@@ -34,7 +34,7 @@ day12_1 :: IO ()
 day12_1 = do
   contents <- lines <$> readFile "input/day12.txt"
   let grid = listVertices contents
-      edgeCoords = [(x, y) | x <- [0 .. length grid - 1], y <- [0 .. length (fst . fromJust $ uncons grid) - 1]]
+      edgeCoords = [(x, y) | x <- [0 .. length grid - 1], y <- [0 .. length (head grid) - 1]]
       edgeList = [(x, y, z) | ((x, y), z) <- zip (concat grid) (map (getEdges grid) edgeCoords)]
       (graph, nodeFromVertex, _) = graphFromEdges edgeList
       plots = scc graph