Day 3

Day3/puzzle1.hs

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+import Data.List.Split (splitOn)
+import Data.Char (isDigit)
+import Text.Regex.TDFA (getAllTextMatches, (=~))
+
+sumMul :: [String] -> Int
+sumMul xs = let vals = map (splitOn "," . filter (`elem` "0123456789,")) xs
+            in  sum $ map (product . map read) vals
+
+main = do
+    contents <- readFile "day3.txt"
+    let mults = getAllTextMatches (contents =~ "mul\\([0-9]+,[0-9]+\\)") :: [String]
+    print $ sumMul mults

Day3/puzzle2.hs

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+import Data.List (isPrefixOf)
+import Data.List.Split (split, splitOn, startsWith)
+import Data.Char (isDigit)
+import Text.Regex.TDFA (getAllTextMatches, (=~))
+
+sumMul :: [String] -> Int
+sumMul xs = let vals = map (splitOn "," . filter (`elem` "0123456789,")) xs
+            in  sum $ map (product . map read) vals
+
+filterDonts :: [String] -> String
+filterDonts = concat . filter (not . isPrefixOf "don't()") . concatMap (split (startsWith "do()"))
+
+main = do
+    contents <- split (startsWith "don't()") <$> readFile "day3.txt"
+    let mults = getAllTextMatches (filterDonts contents =~ "mul\\([0-9]+,[0-9]+\\)") :: [String]
+    print $ sumMul mults