mass rename

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

day04.hs

@@ -0,0 +1,29 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+import Data.Char (isDigit)
+import Data.Either (rights)
+import Data.Maybe (fromJust)
+import Data.Text (Text)
+import qualified Data.Text as T (lines, stripPrefix)
+import qualified Data.Text.Read as T (decimal)
+import Lib (readFile')
+
+main :: IO ()
+main = do
+  input <- rights . map parse . T.lines <$> readFile' "day4.in"
+  putStr "Q1: "
+  print $ q1 input
+  putStr "Q2: "
+  print $ q2 input
+
+parse :: Text -> Either String ((Int, Int), (Int, Int))
+parse rest = do
+  (a, rest) <- T.decimal rest
+  (b, rest) <- T.decimal $ fromJust $ T.stripPrefix "-" rest
+  (c, rest) <- T.decimal $ fromJust $ T.stripPrefix "," rest
+  (d, rest) <- T.decimal $ fromJust $ T.stripPrefix "-" rest
+  return ((a, b), (c, d))
+
+q1, q2 :: [((Int, Int), (Int, Int))] -> Int
+q1 = length . filter (\((a, b), (c, d)) -> a >= c && b <= d || c >= a && d <= b)
+q2 = length . filter (\((a, b), (c, d)) -> b >= c && a <= d)