Solve day 1 with Haskell

day1/Part1.hs

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+module Part1
+  ( parseFileString,
+    quickSort,
+  )
+where
+
+split :: [Int] -> ([Int], [Int])
+split mylist = case mylist of
+  [] -> ([], [])
+  x : xs ->
+    let (evens, odds) = split xs
+     in (x : odds, evens)
+
+parseFileString :: String -> ([Int], [Int])
+parseFileString file_string = split parsed_word_list
+  where
+    parsed_word_list = [read word :: Int | word <- words file_string]
+
+quickSort :: [Int] -> [Int]
+quickSort [] = []
+quickSort (x : xs) = smallerSorted ++ [x] ++ biggerSorted
+  where
+    smallerSorted = quickSort [a | a <- xs, a <= x]
+    biggerSorted = quickSort [a | a <- xs, a > x]

day1/Part2.hs

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+module Part2 where
+
+import Data.Map qualified as Map
+
+getValueCounts :: [Int] -> Map.Map Int Int
+getValueCounts [] = Map.empty
+getValueCounts (x : xs) =
+  let xsMap = getValueCounts xs
+      newCount = Map.findWithDefault 0 x xsMap + 1
+   in Map.insert x newCount xsMap
+
+getSimilarityScore :: [Int] -> Map.Map Int Int -> Int
+getSimilarityScore [] map = 0
+getSimilarityScore (x : xs) map = xScore + getSimilarityScore xs map
+  where
+    xScore = x * Map.findWithDefault 0 x map

day1/README.md

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+# Day 1
+
+## Instructions
+
+From this directory open a terminal and execute:
+
+```sh
+runhaskell day1.hs
+```
+
+The solution for each section will be printed to the terminal output.
+
+## Notes
+
+This is my first attempt at writing Haskell code.
+I've always wanted to try a formal functional programming language, and I've heard of Haskell through using tools like XMonad and Pandoc. 
+Since I use Pandoc regularly I thought Haskell would be a useful skill to have in case I ever need to contribute.
+I also am interested in the functional programming paradigm and want to adapt my thought processes to write cleaner code.
+I thought day 1 would be a good day to try Haskell, and something that would've taken me 10 minutes in any programming language I know really took me a long time. 
+This is definitely not good, clean, idiomatic Haskell, but it is a start!
+

day1/day1.hs

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+import Part1
+import Part2 (getSimilarityScore, getValueCounts)
+import System.IO
+
+main = do
+  inputs <- readFile "inputs.txt"
+  let (listA, listB) = parseFileString inputs
+
+  -- Solve part 1
+  let sortedListA = quickSort listA
+  let sortedListB = quickSort listB
+  let distances = [abs (a - b) | (a, b) <- zip sortedListA sortedListB]
+  let distance = sum distances
+  putStrLn "The solution to part 1 is: "
+  print distance
+
+  -- Solve part 2
+  let bMap = getValueCounts sortedListB
+  let score = getSimilarityScore sortedListA bMap
+  putStrLn "The solution to part 2 is: "
+  print score