feat: solve part 1 day 5

app/Day5.hs

@@ -0,0 +1,45 @@
+module Main where
+
+import System.Environment (getArgs)
+
+main :: IO ()
+main = do
+  input <- readFile . head =<< getArgs
+  putStrLn $ unwords ["Part 1:", show $ part1 input]
+  putStrLn $ unwords ["Part 2:", show $ part2 input]
+
+part1 :: String -> Int
+part1 = length . uncurry (filter . isFresh) . parse
+  where
+    isFresh :: [(Int, Int)] -> Int -> Bool
+    isFresh fresh ing = any (contained ing) fresh
+
+    contained :: Int -> (Int, Int) -> Bool
+    contained a (x, y) = x <= a && a <= y
+
+parse :: String -> ([(Int, Int)], [Int])
+parse = (\(ranges, ingredients) -> ((map parseRange ranges), map read (drop 1 ingredients))) . span (/= "") . lines
+  where
+    parseRange :: String -> (Int, Int)
+    parseRange s = case span (/= '-') s of
+      (start, '-' : end) -> (read start, read end)
+      _ -> error $ "parseRange: expected a string on the form \"NUM-NUM\", got \"" <> s <> "\""
+
+part2 :: String -> Int
+part2 = error "Not implemented"
+
+testInput :: String
+testInput =
+  unlines
+    [ "3-5",
+      "10-14",
+      "16-20",
+      "12-18",
+      "",
+      "1",
+      "5",
+      "8",
+      "11",
+      "17",
+      "32"
+    ]