Day 1! Off to a good start (I hope)

2022/aoc2022.cabal

@@ -32,3 +32,4 @@ executable aoc2022
     build-depends:    base ^>=4.16.3.0
     hs-source-dirs:   app
     default-language: Haskell2010
+    other-modules:    Day1.Main

2022/app/Day1/Main.hs

@@ -0,0 +1,32 @@
+module Day1.Main (main) where
+
+import Data.List
+import System.IO
+import Control.Monad
+
+main :: IO ()
+main = do
+    putStrLn "Day 1"
+
+    handle <- openFile "app/Day1/input" ReadMode
+    contents <- hGetContents handle
+    
+    let r1 = part1 contents
+    putStrLn $ "part 1: " ++ show r1
+    
+    let r2 = part2 contents
+    putStrLn $ "part 2: " ++ show r2
+
+parseInput :: String -> [Int]
+parseInput contents = map sum foodItems
+    where
+        input = lines contents
+        elves = foldr (\a b -> if a == "" then [] : b else (a : head b) : tail b) [[]] input
+        foodItems = (map . map) (read :: String -> Int) elves
+
+part1 :: String -> Int
+part1 = maximum . parseInput
+
+part2 :: String -> Int
+part2 = sum . (take 3) . reverse . sort . parseInput
+

2022/app/Main.hs

@@ -1,4 +1,7 @@
 module Main where
 
+import qualified Day1.Main as Day1
+
 main :: IO ()
-main = putStrLn "Hello, Haskell!"
+main = do
+    Day1.main

2022/cabal.config

@@ -0,0 +1,13 @@
+remote-repo-cache: /build/.cabal/packages
+world-file: /build/.cabal/world
+extra-prog-path: /build/.cabal/bin
+build-summary: /build/.cabal/logs/build.log
+remote-build-reporting: none
+jobs: $ncpus
+installdir: /build/.cabal/bin
+haddock
+init
+install-dirs user
+install-dirs global
+program-locations
+program-default-options

2022/default.nix

@@ -21,5 +21,16 @@ pkgs.stdenv.mkDerivation rec {
     if pkgs.stdenv.isLinux
     then "${pkgs.glibcLocales}/lib/locale/locale-archive"
     else "";
+  src = ./.;
+
+  # This currently doesn't work yet.
+  buildPhase = ''
+    export HOME=$TMP
+    mkdir -p $TMP/.cabal $out/bin
+    cp cabal.config $TMP/.cabal/config
+    cabal build
+    ln -s dist-newstyle/build/x86_64-linux/ghc-9.2.4/aoc2022-0.1.0.0/x/aoc2022/build/aoc2022/aoc2022 $out/bin/aoc2022
+  '';
+        
 }