Added split package to dev env

5/solution.hs

@@ -1,9 +1,17 @@
 import Data.List
+import Data.List.Split
 import Control.Monad (join)
 import Control.Concurrent
 
 main :: IO ()
-main = readFile "5/riley.txt" >>= print . solve . parse . lines
+main = do 
+    input <- readFile "5/example.txt" 
+    let x = parse $ lines input
+    print $ f x
+    print $ g x
+    where
+        f = length . nub . solve . filter (not . diagonal)
+        g = length . nub . solve
 
 parse :: [String] -> [(Point,Point)]
 parse = map (parseLine . words)
@@ -16,7 +24,7 @@ parseLine [ s, "->", e ] = (a, b)
 toRange :: (Point,Point) -> [Point]
 toRange (a @ (xa,ya), b @ (xb,yb))
     | diagonal (a,b) = makeDiagonal a b
-    | otherwise       = [ (x,y) | x <- [ x1 .. x2 ], y <- [ y1 .. y2 ] ]
+    | otherwise      = [ (x,y) | x <- [ x1 .. x2 ], y <- [ y1 .. y2 ] ]
     where
         x1 = min xa xb
         x2 = max xa xb
@@ -26,16 +34,11 @@ toRange (a @ (xa,ya), b @ (xb,yb))
 parseCoord :: String -> (Int,Int)
 parseCoord l = (head n, last n)
     where
-        n = map read $ words [ if c == ',' then ' ' else c | c <- l ]
+        n = map read . wordsBy (== ',') $ l
 
-solve :: [(Point,Point)] -> (Int,Int)
-solve i = (f i, g i)
-    where f = length . nub . overlapping . filter (not . diagonal)
-          g = length . nub . overlapping
-
-overlapping :: [(Point, Point)] -> [Point]
-overlapping [_] = []
-overlapping (p:ps) = overlapping' p ps ++ overlapping ps
+solve :: [(Point, Point)] -> [Point]
+solve [_] = []
+solve (p:ps) = overlapping' p ps ++ solve ps
 
 overlapping' :: (Point, Point) -> [(Point, Point)] -> [Point]
 overlapping' _ [] = []

shell.nix

@@ -1,7 +1,8 @@
 { pkgs ? import <nixpkgs> {} }: pkgs.mkShell {
     nativeBuildInputs = with pkgs; [
         haskell-language-server
-        cabal-install
-        ghc
+        (ghc.withPackages (pkgs: with pkgs; [
+            split
+        ]))
     ];
 }