From 7e0c66b8f6f142420041972620f3795c83a4c22f Mon Sep 17 00:00:00 2001
From: Andreas Grois <andi@grois.info>
Date: Wed, 21 Dec 2022 00:05:25 +0100
Subject: Day8 partial input parsing.

---
 Day8/CHANGELOG.md |  5 +++++
 Day8/Day8.cabal   | 34 ++++++++++++++++++++++++++++++++++
 Day8/app/Main.hs  | 41 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 80 insertions(+)
 create mode 100644 Day8/CHANGELOG.md
 create mode 100644 Day8/Day8.cabal
 create mode 100644 Day8/app/Main.hs

diff --git a/Day8/CHANGELOG.md b/Day8/CHANGELOG.md
new file mode 100644
index 0000000..e61d908
--- /dev/null
+++ b/Day8/CHANGELOG.md
@@ -0,0 +1,5 @@
+# Revision history for Day8
+
+## 0.1.0.0 -- YYYY-mm-dd
+
+* First version. Released on an unsuspecting world.
diff --git a/Day8/Day8.cabal b/Day8/Day8.cabal
new file mode 100644
index 0000000..765b9f1
--- /dev/null
+++ b/Day8/Day8.cabal
@@ -0,0 +1,34 @@
+cabal-version:      2.4
+name:               Day8
+version:            0.1.0.0
+
+-- A short (one-line) description of the package.
+-- synopsis:
+
+-- 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:
+author:             Andreas Grois
+maintainer:         andi@grois.info
+
+-- A copyright notice.
+-- copyright:
+-- category:
+extra-source-files: CHANGELOG.md
+
+executable Day8
+    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 ^>=4.16.3.0
+    hs-source-dirs:   app
+    default-language: Haskell2010
diff --git a/Day8/app/Main.hs b/Day8/app/Main.hs
new file mode 100644
index 0000000..fc36d66
--- /dev/null
+++ b/Day8/app/Main.hs
@@ -0,0 +1,41 @@
+module Main (main) where
+
+import System.Environment ( getArgs )
+
+main :: IO ()
+main = getArgs >>= readFile . head >>= print . solveDay8
+
+solveDay8 :: String -> String
+solveDay8 = formatDay8Result . fmap solveDay8Parts . parseDay8Input
+
+formatDay8Result :: Maybe (Int, Int) -> String
+formatDay8Result Nothing = "Input didn't parse. Check that it is a rectangular grid with values from 0-9."
+formatDay8Result (Just (p1, p2)) = "Part 1: " ++ show p1 ++ ", Part 2: " ++ show p2
+
+newtype Day8Input = Day8Input [[Height]] -- but with guarantee that it's rectangular
+
+data Height = Zero | One | Two | Three | Four | Five | Six | Seven | Eight | Nine
+    deriving (Eq, Ord)
+
+heightFromChar :: Char -> Maybe Height -- this could also be done using the Enum typeclass' toEnum function and an intermediate Int
+heightFromChar '0' = Just Zero
+heightFromChar '1' = Just One
+heightFromChar '2' = Just Two
+heightFromChar '3' = Just Three
+heightFromChar '4' = Just Four
+heightFromChar '5' = Just Five
+heightFromChar '6' = Just Six
+heightFromChar '7' = Just Seven
+heightFromChar '8' = Just Eight
+heightFromChar '9' = Just Nine
+heightFromChar _ = Nothing
+
+validateDay8Input :: [[Height]] -> Maybe Day8Input
+validateDay8Input [] = Nothing
+validateDay8Input (h:hs) = if all ((== length h) . length) hs then Just $ Day8Input $ h:hs else Nothing
+
+parseDay8Input :: String -> Maybe Day8Input
+parseDay8Input = (=<<) validateDay8Input . mapM (mapM heightFromChar) . lines
+
+solveDay8Parts :: Day8Input -> (Int, Int)
+solveDay8Parts = undefined
\ No newline at end of file
-- 
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