More tidying

diff --git a/advent17.hs b/advent17.hs
index c99b8da2aabdac93d5b5344110d0a3209510fece..d8be772aacbe906e1386ab906dc350d7bf4d3841 100644 (file)
--- a/advent17.hs
+++ b/advent17.hs
@@ -61,13 +61,14 @@ successors state = [Agendum {position = step p0 ld,
         legalDoors = filter (isLegalPos . (step p0)) doors
 
 openDoors :: String -> String
-openDoors h = (u h) ++ (d h) ++ (l h) ++ (r h)
-
-u h = if h!!0 `elem` "bcdef" then "U" else ""
-d h = if h!!1 `elem` "bcdef" then "D" else ""
-l h = if h!!2 `elem` "bcdef" then "L" else ""
-r h = if h!!3 `elem` "bcdef" then "R" else ""
-
+openDoors h = up ++ down ++ left ++ right
+    where
+        up    = if h!!0 `elem` "bcdef" then "U" else ""
+        down  = if h!!1 `elem` "bcdef" then "D" else ""
+        left  = if h!!2 `elem` "bcdef" then "L" else ""
+        right = if h!!3 `elem` "bcdef" then "R" else ""
+
+step :: Position -> Char -> Position
 step (r, c) 'U' = (r-1, c)
 step (r, c) 'D' = (r+1, c)
 step (r, c) 'L' = (r, c-1)