haskell: 2023 20 parse

2023/haskell/aoc2023.cabal

@@ -31,6 +31,7 @@ library
     Day11
     Day12
     Day15
+    Day20
     Day24
 
   other-modules:

2023/haskell/solutions/Day20.hs

@@ -0,0 +1,57 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RecordWildCards #-}
+module Day20 where
+
+import Data.Void (Void)
+import Data.Text (Text)
+import Data.Bifunctor (first)
+import Text.Megaparsec (Parsec, (<|>), errorBundlePretty, runParser, eof, many, choice, sepBy)
+import Text.Megaparsec.Char (char, alphaNumChar, space, string)
+import Text.Megaparsec.Char.Lexer ()
+
+
+data ModType
+  = Cast -- Broadcast
+  | Flip -- Flip-Flop
+  | Conj -- Conjuntion
+  deriving Show
+
+data Mod = Mod
+  { mName :: !String
+  , mType :: !ModType
+  , mNext :: ![String]
+  } deriving Show
+
+type Parser = Parsec Void Text
+
+a :: Text
+a =
+  "broadcaster -> a, b, c\n\
+  \%a -> b\n\
+  \%b -> c\n\
+  \%c -> inv\n\
+  \&inv -> a\n"
+
+b :: Text
+b =
+  "broadcaster -> a\n\
+  \%a -> inv, con\n\
+  \&inv -> b\n\
+  \%b -> con\n\
+  \&con -> output\n"
+
+parse :: Text -> Either String [Mod]
+parse = first errorBundlePretty . runParser ms ""
+  where
+    m :: Parser Mod
+    m = do
+      mType <- choice [ Flip <$ char '%', Conj <$ char '&' ] <|> pure Cast
+      mName <- many alphaNumChar <* space <* string "->" <* space
+      mNext <- (many alphaNumChar `sepBy` string ", ") <* space
+      return $ Mod {..}
+    ms :: Parser [Mod]
+    ms = many m <* eof
+
+-- >>> parse a
+-- Right [Mod {mName = "broadcaster", mType = Cast, mNext = ["a","b","c"]},Mod {mName = "a", mType = Flip, mNext = ["b"]},Mod {mName = "b", mType = Flip, mNext = ["c"]},Mod {mName = "c", mType = Flip, mNext = ["inv"]},Mod {mName = "inv", mType = Conj, mNext = ["a"]}]
+