Improve some code

src/Day01.hs

@@ -1,4 +1,4 @@
-{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
+{-# OPTIONS_GHC -Wno-incomplete-uni-patterns -Wno-x-partial #-}
 
 module Day01
   ( day01_1,
@@ -6,15 +6,14 @@ module Day01
   )
 where
 
-import Data.List (group, sort, transpose, uncons)
+import Data.List (group, sort, transpose)
-import Data.Maybe (fromJust)
 
 listDistance :: [Int] -> [Int] -> Int
 listDistance xs ys = sum $ map abs $ zipWith (-) (sort xs) (sort ys)
 
 similarityScore :: [Int] -> [Int] -> Int
 similarityScore xs ys =
-  let elemsY = [(fst . fromJust $ uncons y, length y) | y <- (group . sort) ys]
+  let elemsY = [(head y, length y) | y <- (group . sort) ys]
    in sum [x * snd y | x <- xs, y <- elemsY, x == fst y]
 
 parseInput :: IO [[Int]]

src/Day06.hs

@@ -1,10 +1,12 @@
+{-# OPTIONS_GHC -Wno-x-partial #-}
+
 module Day06
   ( day06_1,
     day06_2,
   )
 where
 
-import Data.List (elemIndex, uncons)
+import Data.List (elemIndex)
 import Data.Maybe (fromJust, fromMaybe, isJust)
 
 type Grid = [String]
@@ -36,7 +38,7 @@ getGridVal :: Position -> Grid -> Char
 getGridVal (x, y) grid = (grid !! x) !! y
 
 isInside :: Position -> Grid -> Bool
-isInside (x, y) grid = x >= 0 && y >= 0 && x < length grid && y < length (fst . fromJust $ uncons grid)
+isInside (x, y) grid = x >= 0 && y >= 0 && x < length grid && y < length (head grid)
 
 getNextPosition :: Position -> Direction -> Grid -> (Position, Direction)
 getNextPosition (x, y) U grid =
@@ -64,12 +66,6 @@ getNextPosition (x, y) L grid =
         then getNextPosition (x, y) U grid
         else (newPos, L)
 
--- markVisited :: Position -> Char -> Grid -> Grid
--- markVisited (x, y) c grid =
---  let row = grid !! x
---      newRow = take y row ++ [c] ++ drop (y + 1) row
---   in take x grid ++ [newRow] ++ drop (x + 1) grid
---
 markVisited :: Position -> Char -> Grid -> Grid
 markVisited (x, y) c grid =
   let gridVal = getGridVal (x, y) grid
@@ -100,14 +96,14 @@ checkGridLoop startPosition direction grid =
 
 setGridObstacles :: Position -> Grid -> [Grid]
 setGridObstacles startPosition grid =
-  let positions = [(x, y) | x <- [0 .. (length grid - 1)], y <- [0 .. (length (fst . fromJust $ uncons grid) - 1)], (x, y) /= startPosition, getGridVal (x, y) grid == 'X']
+  let positions = [(x, y) | x <- [0 .. (length grid - 1)], y <- [0 .. (length (head grid) - 1)], (x, y) /= startPosition, getGridVal (x, y) grid == 'X']
    in zipWith (`markVisited` '#') positions (replicate (length positions) grid)
 
 parseInput :: IO (Int, Int, Direction, [String])
 parseInput = do
   contents <- lines <$> readFile "input/day6.txt"
   let (x, y) =
-        (\a b c d -> fst . fromJust . uncons $ filter ((>= 0) . fst) [a, b, c, d])
+        (\a b c d -> head $ filter ((>= 0) . fst) [a, b, c, d])
           <$> getStartPosition 'v'
           <*> getStartPosition '^'
           <*> getStartPosition '<'

src/Day08.hs

@@ -1,3 +1,5 @@
+{-# OPTIONS_GHC -Wno-x-partial #-}
+
 module Day08
   ( day08_1,
     day08_2,
@@ -6,8 +8,6 @@ where
 
 import Control.Applicative
 import Data.Bifunctor (bimap)
-import Data.List (uncons)
-import Data.Maybe (fromJust)
 import Data.Set (fromList)
 
 type Freq = Char
@@ -66,7 +66,7 @@ parseInput = do
   contents <- lines <$> readFile "input/day8.txt"
   let antennas = getAntennas contents
       x = length contents
-      y = length $ fst . fromJust $ uncons contents
+      y = length $ head contents
   return (x, y, antennas)
 
 day08_1 :: IO ()

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)]
+      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, (fst . fromJust $ uncons value) == (fst . fromJust $ uncons (fst x))]
+   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

src/Day13.hs

@@ -1,4 +1,4 @@
-{-# OPTIONS_GHC -Wno-type-defaults #-}
+{-# OPTIONS_GHC -Wno-type-defaults -Wno-x-partial #-}
 
 module Day13
   ( day13_1,
@@ -8,10 +8,9 @@ where
 
 import Data.Char (isDigit)
 import Data.Either (fromRight)
-import Data.List (uncons)
 import Data.List.Split (chunksOf, splitOn)
 import Data.Matrix (Matrix, fromLists, rref, toList, zero)
-import Data.Maybe (fromJust, mapMaybe)
+import Data.Maybe (mapMaybe)
 
 isAlmostInt :: (RealFrac a) => a -> Bool
 isAlmostInt x =
@@ -25,14 +24,14 @@ multRes xs = xs
 getMatrix :: (Read a) => String -> Matrix a
 getMatrix s =
   let nValues = map (map read . splitOn ",") . splitOn ":" . drop 1 $ filter (\x -> isDigit x || x == ',' || x == ':') s
-      eq1 = map (fst . fromJust . uncons) nValues
+      eq1 = map head nValues
       eq2 = map last nValues
    in fromLists [eq1, eq2]
 
 getMatrix' :: (Num a, Read a) => String -> Matrix a
 getMatrix' s =
   let nValues = map (map read . splitOn ",") . splitOn ":" . drop 1 $ filter (\x -> isDigit x || x == ',' || x == ':') s
-      eq1 = multRes $ map (fst . fromJust . uncons) nValues
+      eq1 = multRes $ map head nValues
       eq2 = multRes $ map last nValues
    in fromLists [eq1, eq2]
 

src/Day15.hs

@@ -1,8 +1,8 @@
-{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
+{-# OPTIONS_GHC -Wno-incomplete-uni-patterns -Wno-x-partial #-}
 
 module Day15 (day15_1) where
 
-import Data.List (elemIndex, elemIndices, transpose, uncons)
+import Data.List (elemIndex, elemIndices, transpose)
 import Data.List.Split (splitOn)
 import Data.Maybe (fromJust, fromMaybe, isJust)
 
@@ -70,8 +70,8 @@ shiftUp p1 grid =
             then markPosition p1 '.' (markPosition p2 '@' (markPosition p3 'O' grid))
             else
               let column = reverse $ transpose grid !! snd p1
-                  nextDot = fst . fromMaybe (-1, []) $ uncons $ dropWhile (< length column - fst p1) $ elemIndices '.' column
+                  nextDot = head $ dropWhile (< length column - fst p1) $ elemIndices '.' column
-                  nextHash = fst . fromMaybe (-1, []) $ uncons $ dropWhile (< length column - fst p1) $ elemIndices '#' column
+                  nextHash = head $ dropWhile (< length column - fst p1) $ elemIndices '#' column
                in if nextDot == -1 || nextDot > nextHash
                     then grid
                     else markPosition p1 '.' (markPosition p2 '@' (markPosition (length column - 1 - nextDot, snd p1) 'O' grid))
@@ -88,8 +88,8 @@ shiftRight p1 grid =
             then markPosition p1 '.' (markPosition p2 '@' (markPosition p3 'O' grid))
             else
               let row = grid !! fst p1
-                  nextDot = fst . fromMaybe (-1, []) $ uncons $ dropWhile (< snd p1) $ elemIndices '.' row
+                  nextDot = head $ dropWhile (< snd p1) $ elemIndices '.' row
-                  nextHash = fst . fromMaybe (-1, []) $ uncons $ dropWhile (< snd p1) $ elemIndices '#' row
+                  nextHash = head $ dropWhile (< snd p1) $ elemIndices '#' row
                in if nextDot == -1 || nextDot > nextHash
                     then grid
                     else markPosition p1 '.' (markPosition p2 '@' (markPosition (fst p1, nextDot) 'O' grid))
@@ -106,8 +106,8 @@ shiftDown p1 grid =
             then markPosition p1 '.' (markPosition p2 '@' (markPosition p3 'O' grid))
             else
               let column = transpose grid !! snd p1
-                  nextDot = fst . fromMaybe (-1, []) $ uncons $ dropWhile (< fst p1) $ elemIndices '.' column
+                  nextDot = head $ dropWhile (< fst p1) $ elemIndices '.' column
-                  nextHash = fst . fromMaybe (-1, []) $ uncons $ dropWhile (< fst p1) $ elemIndices '#' column
+                  nextHash = head $ dropWhile (< fst p1) $ elemIndices '#' column
                in if nextDot == -1 || nextDot > nextHash
                     then grid
                     else markPosition p1 '.' (markPosition p2 '@' (markPosition (nextDot, snd p1) 'O' grid))
@@ -124,8 +124,8 @@ shiftLeft p1 grid =
             then markPosition p1 '.' (markPosition p2 '@' (markPosition p3 'O' grid))
             else
               let row = reverse $ grid !! fst p1
-                  nextDot = fst . fromMaybe (-1, []) $ uncons $ dropWhile (< length row - snd p1) $ elemIndices '.' row
+                  nextDot = head $ dropWhile (< length row - snd p1) $ elemIndices '.' row
-                  nextHash = fst . fromMaybe (-1, []) $ uncons $ dropWhile (< length row - snd p1) $ elemIndices '#' row
+                  nextHash = head $ dropWhile (< length row - snd p1) $ elemIndices '#' row
                in if nextDot == -1 || nextDot > nextHash
                     then grid
                     else markPosition p1 '.' (markPosition p2 '@' (markPosition (fst p1, length row - 1 - nextDot) 'O' grid))
@@ -195,7 +195,7 @@ gpsCoords (x, y) = 100 * x + y
 
 boxCoords :: Grid -> [Int]
 boxCoords grid =
-  let coords = [(x, y) | x <- [0 .. length grid - 1], y <- [0 .. length (fst . fromJust $ uncons grid) - 1], getGridVal (x, y) grid == 'O']
+  let coords = [(x, y) | x <- [0 .. length grid - 1], y <- [0 .. length (head grid) - 1], getGridVal (x, y) grid == 'O']
    in map gpsCoords coords
 
 day15_1 :: IO ()

src/Day17.hs

@@ -1,14 +1,11 @@
-{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
+{-# OPTIONS_GHC -Wno-incomplete-uni-patterns -Wno-type-defaults -Wno-x-partial #-}
-{-# OPTIONS_GHC -Wno-type-defaults #-}
 
 module Day17 (day17_1, day17_2) where
 
 import Control.Monad.State
 import Data.Bits
 import Data.Char (isDigit)
-import Data.List (uncons)
 import Data.List.Split (splitOn)
-import Data.Maybe (fromJust)
 
 type Program = [Int]
 
@@ -132,7 +129,7 @@ parseInput = do
 day17_1 :: IO ()
 day17_1 = do
   (registers, prog) <- parseInput
-  let computer = Computer {registerA = fst . fromJust $ uncons registers, registerB = registers !! 1, registerC = registers !! 2, pointer = 0, program = prog, output = ""}
+  let computer = Computer {registerA = head registers, registerB = registers !! 1, registerC = registers !! 2, pointer = 0, program = prog, output = ""}
   putStr "Day 17, Puzzle 1 solution: "
   print . drop 1 . output $ execState runProgram computer
 
@@ -143,4 +140,4 @@ day17_2 = do
       regA = [805464 * 2 ^ 27 ..] -- Threshold derived empirically, a better threshold must be possible because this is very slow, but got the correct answer.
   putStrLn $
     "Day 17, Puzzle 2 solution: "
-      ++ show (fst . fromJust . uncons $ dropWhile (\x -> not (checkIfCreatesCopy computer {registerA = x})) regA)
+      ++ show (head $ dropWhile (\x -> not (checkIfCreatesCopy computer {registerA = x})) regA)