Golf :)

hs/src/Day25.hs

@@ -2,6 +2,7 @@
 Module:         Day25
 Description:    <https://adventofcode.com/2022/day/25 Day 25: Full of Hot Air>
 -}
+{-# LANGUAGE MultiWayIf #-}
 module Day25 (day25) where
 
 import Data.Char (digitToInt, intToDigit)
@@ -10,11 +11,8 @@ import qualified Data.Text as T (foldl', lines, unfoldr, reverse)
 
 day25 :: Text -> Text
 day25 = T.reverse . T.unfoldr g . sum . map (T.foldl' f 0) . T.lines where
-    f k '=' = 5 * k - 2
-    f k '-' = 5 * k - 1
-    f k c = 5 * k + digitToInt c
+    f k c = 5 * k + if | '=' <- c -> -2 | '-' <- c -> -1 | otherwise -> digitToInt c
     g 0 = Nothing
-    g n = let (q, r) = (n + 2) `divMod` 5 in Just (intToSnafuDigit $ r - 2, q)
-    intToSnafuDigit (-2) = '='
-    intToSnafuDigit (-1) = '-'
-    intToSnafuDigit d = intToDigit d
+    g n = Just (c, q) where
+        (q, r) = (n + 2) `divMod` 5
+        c | 0 <- r = '=' | 1 <- r = '-' | otherwise = intToDigit $ r - 2