diff --git a/hs/app/Main.hs b/hs/app/Main.hs
index cdfac72..de42bb1 100644
--- a/hs/app/Main.hs
+++ b/hs/app/Main.hs
@@ -1,34 +1,24 @@
 module Main where
 
-import Options.Applicative
+import           Control.Monad
 
-import Aoc.Y2019
-import Aoc.Y2020
+import           Options.Applicative
 
-data Settings = Settings
-  { function :: FilePath -> IO ()
-  , filename :: FilePath
-  }
+import           Aoc.Day             (Day (..))
+import qualified Aoc.Y2019           as Y2019
+import qualified Aoc.Y2020           as Y2020
 
-solutions :: Parser (FilePath -> IO ())
-solutions = subparser $ mconcat $ map (\(name, func) -> command name (info (pure func) mempty))
-  [ ("2019_01", solve201901)
-  , ("2019_02", solve201902)
-  , ("2019_03", solve201903)
-  , ("2019_04", solve201904)
-  , ("2019_05", solve201905)
-  , ("2020_01", solve202001)
-  ]
+toCommand :: Day -> Mod CommandFields (IO ())
+toCommand (DayPure name f) = command name $ info (helper <*> pure f) mempty
+toCommand (DayFile name f) = command name $ info (helper <*> p) mempty
+  where
+    p = f <$> strArgument (metavar "INPUTFILE")
 
-parser :: Parser Settings
-parser = Settings
-  <$> solutions
-  <*> strArgument (metavar "INPUTFILE")
+parser :: Parser (IO ())
+parser = subparser $ mconcat $ map toCommand $ Y2019.days ++ Y2020.days
 
-opts :: ParserInfo Settings
+opts :: ParserInfo (IO ())
 opts = info (helper <*> parser) $ fullDesc <> failureCode 1
 
 main :: IO ()
-main = do
-  settings <- customExecParser (prefs showHelpOnEmpty) opts
-  function settings $ filename settings
+main = join $ customExecParser (prefs showHelpOnEmpty) opts
diff --git a/hs/src/Aoc/Y2019.hs b/hs/src/Aoc/Y2019.hs
index 4f980b4..255d7e0 100644
--- a/hs/src/Aoc/Y2019.hs
+++ b/hs/src/Aoc/Y2019.hs
@@ -1,13 +1,8 @@
 module Aoc.Y2019
-  ( solve201901
-  , solve201902
-  , solve201903
-  , solve201904
-  , solve201905
+  ( days
   ) where
 
-import Aoc.Y2019.A01
-import Aoc.Y2019.A02
-import Aoc.Y2019.A03
-import Aoc.Y2019.A04
-import Aoc.Y2019.A05
+import           Aoc.Day
+
+days :: [Day]
+days = []
diff --git a/hs/src/Aoc/Y2020.hs b/hs/src/Aoc/Y2020.hs
index 1438bc6..c1513e4 100644
--- a/hs/src/Aoc/Y2020.hs
+++ b/hs/src/Aoc/Y2020.hs
@@ -1,5 +1,11 @@
 module Aoc.Y2020
-  ( solve202001
+  ( days
   ) where
 
-import Aoc.Y2020.A01
+import           Aoc.Day
+import qualified Aoc.Y2020.D01 as D01
+
+days :: [Day]
+days =
+  [ D01.day
+  ]
diff --git a/hs/src/Aoc/Y2020/A01.hs b/hs/src/Aoc/Y2020/D01.hs
similarity index 83%
rename from hs/src/Aoc/Y2020/A01.hs
rename to hs/src/Aoc/Y2020/D01.hs
index f689ca3..16e5bde 100644
--- a/hs/src/Aoc/Y2020/A01.hs
+++ b/hs/src/Aoc/Y2020/D01.hs
@@ -1,8 +1,10 @@
-module Aoc.Y2020.A01
-  ( solve202001
+module Aoc.Y2020.D01
+  ( day
   ) where
 
-import Control.Monad
+import           Control.Monad
+
+import           Aoc.Day
 
 findPair :: [Integer] -> (Integer, Integer)
 findPair l = head $ do
@@ -30,3 +32,6 @@ solve202001 f = do
   let (y1, y2, y3) = findTriple values
   putStrLn ">> Part 2"
   putStrLn $ show y1 ++ " * " ++ show y2 ++ " * " ++ show y3 ++ " = " ++ show (y1 * y2 * y3)
+
+day :: Day
+day = dayFile "2020_01" solve202001