day1 done

AoC2022.cabal

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+cabal-version:      2.4
+name:               AoC2022
+version:            0.1.0.0
+
+-- A short (one-line) description of the package.
+synopsis: Solutions for Advent of Code 2022
+
+-- A longer description of the package.
+-- description:
+
+-- A URL where users can report bugs.
+-- bug-reports:
+
+-- The license under which the package is released.
+license:            CC-BY-NC-ND-4.0
+author:             Stefan Dresselhaus
+maintainer:         stefan@dresselhaus.cloud
+
+-- A copyright notice.
+-- copyright:
+-- category:
+extra-source-files:
+    CHANGELOG.md
+    README.md
+
+executable Day1
+    main-is:          Main.hs
+
+    -- Modules included in this executable, other than Main.
+    -- other-modules:
+
+    -- LANGUAGE extensions used by modules in this package.
+    -- other-extensions:
+    build-depends:    base ^>=4.14.3.0
+                    , safe
+    hs-source-dirs:   day1
+    default-language: Haskell2010

CHANGELOG.md

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+# Revision history for AoC2022
+
+## 0.1.0.0 -- YYYY-mm-dd
+
+* First version. Released on an unsuspecting world.

day1/Main.hs

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+{-# LANGUAGE LambdaCase #-}
+module Main where
+
+import Data.List as L
+import Data.Maybe
+import Safe
+
+data InputOptions = Elf1
+                  | Elf3
+                  | Quit
+
+
+getInput :: IO InputOptions
+getInput = do
+  putStrLn "Only get top Elf or sum of top 3 Elf? (1/3/q)"
+  getLine >>= \case
+       "1" -> return Elf1
+       "3" -> return Elf3
+       "q" -> return Quit
+       _   -> putStrLn "not understood" >> getInput
+main :: IO ()
+main = getInput >>= \case
+    Quit -> putStrLn "bye!"
+    Elf1 -> interact $
+          (<>"\n")
+        . show
+        . maximum
+        . fmap (sum . mapMaybe (readMay :: String -> Maybe Integer))
+        . splitOn ""
+        . lines
+    Elf3 -> interact $
+          (<>"\n")
+        . show
+        . sum
+        . take 3
+        . sortOn negate
+        . fmap (sum . mapMaybe (readMay :: String -> Maybe Integer))
+        . splitOn ""
+        . lines
+
+
+-- | Split a list into sublists delimited by the given element.
+--
+-- From: https://hackage.haskell.org/package/haskell-gi-0.26.2/docs/src/Data.GI.CodeGen.Util.html#splitOn
+splitOn :: Eq a => a -> [a] -> [[a]]
+splitOn x xs = go xs []
+    where go [] acc = [reverse acc]
+          go (y : ys) acc = if x == y
+                            then reverse acc : go ys []
+                            else go ys (y : acc)