Minor refactoring

chapter4/SlidingPuzzle.hs

@@ -1,3 +1,4 @@
+module SlidingPuzzle where
 -- Solves the sliding puzzle problem (http://en.wikipedia.org/wiki/Sliding_puzzle)
 -- using A* algorithm
 
@@ -88,6 +89,7 @@ type Point = (Int, Int)
 
 -- A sliding puzzle
 -- blank : which item is considered blank
+-- blankPos : position of blank
 -- pzState : the current state of the puzzle
 data Puzzle a = Puzzle { blank :: a, blankPos :: Point, pzState :: Array Point a }
               deriving (Eq, Ord)