changed indent method according to ghc standard

DataModel.hs

@@ -8,31 +8,35 @@ type Frequency = Double
 type Confidence = Double
 
 class Freq a where
-	frequency :: [ItemSet] -> a -> Frequency
+    frequency :: [ItemSet] -> a -> Frequency
 
 data Item = Item String deriving (Eq, Ord)
 instance Show Item where
-	show (Item s) = s --"Item " ++ s
+    show (Item s) = s --"Item " ++ s
 
 data ItemSet = ItemSet (Set Item) deriving (Eq, Ord)
 
 instance Show ItemSet where
-	show (ItemSet x) = foldr ((\y old -> y ++ " " ++ old).show) "" (Set.toList x)
+    show (ItemSet x) =
+        foldr ((\y old -> y ++ " " ++ old).show) "" (Set.toList x)
 
 instance Freq ItemSet where
-	frequency table (ItemSet set) = setCount / fromIntegral (length table) where
-		setCount = fromIntegral $ count table (ItemSet set)
+    frequency table (ItemSet set) =
+        setCount / fromIntegral (length table) where
+            setCount = fromIntegral $ count table (ItemSet set)
 
 count :: [ItemSet] -> ItemSet -> Count
-count table (ItemSet set) = length (filter (\(ItemSet row) -> set `Set.isSubsetOf` row) table)
+count table (ItemSet set) =
+    length (filter isSuperSet table) where
+        isSuperset (ItemSet row) = set `Set.isSubsetOf` row
 
 data Rule = Rule ItemSet ItemSet deriving (Eq)
 
 instance Show Rule where
-	show (Rule a b) = show a ++ "-> " ++ show b
+    show (Rule a b) = show a ++ "-> " ++ show b
 
 instance Freq Rule where
-	frequency table (Rule (ItemSet set1) (ItemSet set2)) = frequency table $ ItemSet (set1 `Set.union` set2)
+    frequency table (Rule (ItemSet set1) (ItemSet set2)) = frequency table $ ItemSet (set1 `Set.union` set2)
 
 confidence :: [ItemSet] -> Rule -> Confidence
 confidence table (Rule x y) = frequency table (Rule x y) / frequency table x