From 41f0b8d511ee53dbd2f298ff00cfcf9b30ee40cb Mon Sep 17 00:00:00 2001
From: George Thomas <georgefsthomas@gmail.com>
Date: Tue, 6 Jan 2026 22:32:11 +0000
Subject: [PATCH] Move some utilities out of `Day4.hs`

---
 haskell/Pre.hs          | 11 +++++++++++
 haskell/Puzzles/Day4.hs |  8 --------
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/haskell/Pre.hs b/haskell/Pre.hs
index e03416b..28ab845 100644
--- a/haskell/Pre.hs
+++ b/haskell/Pre.hs
@@ -39,6 +39,9 @@ module Pre (
     module Text.Megaparsec.Char.Lexer,
     module Text.Pretty.Simple,
     Puzzle (..),
+    (<<$>>),
+    (<<&>>),
+    takeUntil,
     digit,
     digitsToInt,
     listIndex,
@@ -138,6 +141,14 @@ data Puzzle = forall input outputs. (KnownNat (Length outputs), NFData input) =>
     , extraTests :: Bool -> FilePath -> [TestTree IO (input, HList outputs)]
     }
 
+(<<$>>) :: (Functor f1, Functor f2) => (a -> b) -> f1 (f2 a) -> f1 (f2 b)
+(<<$>>) = fmap . fmap
+(<<&>>) :: (Functor f1, Functor f2) => f1 (f2 a) -> (a -> b) -> f1 (f2 b)
+(<<&>>) = flip (<<$>>)
+
+takeUntil :: (Foldable t) => (a -> Bool) -> t a -> [a]
+takeUntil p = foldr (\x xs -> x : if p x then [] else xs) []
+
 digit :: (Token s ~ Char, Num b, MonadParsec e s f) => f b
 digit = fromIntegral . digitToInt <$> digitChar
 
diff --git a/haskell/Puzzles/Day4.hs b/haskell/Puzzles/Day4.hs
index 03dc718..d449ce7 100644
--- a/haskell/Puzzles/Day4.hs
+++ b/haskell/Puzzles/Day4.hs
@@ -123,13 +123,5 @@ noneAccessible (Grid g) = not $ any (elem OutAccessible . fmap snd) g
 countRolls :: Grid InTile -> Int
 countRolls (Grid g) = length $ concatMap (filter (== InRoll) . toList . fmap snd) g
 
-(<<$>>) :: (Functor f1, Functor f2) => (a -> b) -> f1 (f2 a) -> f1 (f2 b)
-(<<$>>) = fmap . fmap
-(<<&>>) :: (Functor f1, Functor f2) => f1 (f2 a) -> (a -> b) -> f1 (f2 b)
-(<<&>>) = flip (<<$>>)
-
-takeUntil :: (Foldable t) => (a -> Bool) -> t a -> [a]
-takeUntil p = foldr (\x xs -> x : if p x then [] else xs) []
-
 unfoldMutual :: (a -> b) -> (b -> a) -> a -> Stream (a, b)
 unfoldMutual f g a = let b = f a in (a, b) :> unfoldMutual f g (g b)