Merge pull request #48 from purescript/fix-warnings

Fix warnings about partial functions

Author: garyb

src/Data/Array.purs

@@ -458,10 +458,10 @@ groupBy :: forall a. (a -> a -> Boolean) -> Array a -> Array (Array a)
 groupBy op = go []
   where
   go :: Array (Array a) -> Array a -> Array (Array a)
-  go acc []     = reverse acc
   go acc xs = case uncons xs of
-                Just o -> let sp = span (op o.head) o.tail
-                          in go ((o.head : sp.init) : acc) sp.rest
+    Just o -> let sp = span (op o.head) o.tail
+              in go ((o.head : sp.init) : acc) sp.rest
+    Nothing -> reverse acc
 
 --------------------------------------------------------------------------------
 -- Set-like operations ---------------------------------------------------------
@@ -474,9 +474,9 @@ nub = nubBy eq
 -- | Remove the duplicates from an array, where element equality is determined
 -- | by the specified equivalence relation, creating a new array.
 nubBy :: forall a. (a -> a -> Boolean) -> Array a -> Array a
-nubBy _ [] = []
 nubBy eq xs = case uncons xs of
                 Just o -> o.head : nubBy eq (filter (\y -> not (o.head `eq` y)) o.tail)
+                Nothing -> []
 
 -- | Calculate the union of two lists.
 -- |