add hlint and apply suggestions

default.nix

@@ -6,6 +6,7 @@ let
       pkgs.haskell.lib.addBuildTools drv (with pkgs.haskellPackages;
         [
           cabal-install
+          hlint
         ]);
   };
 in haskellEnv.overrideAttrs(o: {

lib/Track.hs

@@ -57,7 +57,7 @@ elToPoint c =
         ele = child c >>= element (Name "ele" (Just gpxNS) Nothing) >>= child >>= content
       in Point (Pos lat lon)
          (case ele of
-             e:[] -> Just $ asFloat e
+             [e] -> Just $ asFloat e
              _ -> Nothing)
          (UTCTime (toEnum  60631) 43200)
          (Just 0)
@@ -66,7 +66,7 @@ elToPoint c =
       where
         asFloat v = (read (Data.Text.unpack v) :: Float)
         getAttr name =
-          case (Map.lookup name attrs) of
+          case Map.lookup name attrs of
             Just v -> asFloat v
             _ -> 0
     _ -> mkPoint (Pos 0 0)
@@ -80,7 +80,7 @@ getPoints c =
       element (ns "trk") >>= descendant >>=
       element (ns "trkpt")
   in
-    (List.map elToPoint trkpts)
+    List.map elToPoint trkpts
 
 parse :: String -> Either SomeException [Point]
 parse str = do
@@ -88,4 +88,4 @@ parse str = do
   return (getPoints (fromDocument gpx))
 
 length :: Track -> Int
-length trk = Data.List.length trk
+length = Data.List.length

tests/UnitTest.hs

@@ -28,11 +28,11 @@ xsi:schemaLocation="http://www.topografix.com/GPX/1/1 http://www.topografix.com/
 wrap x = preamble ++ x ++ "</gpx>"
 
 
-onepoint = wrap $
+onepoint = wrap
   "<trk> <trkseg> \n\
   \<trkpt lat=\"51\" lon=\"-0.1\"> </trkpt> \n\
   \</trkseg> </trk>"
-onepointWithAttrs = wrap $
+onepointWithAttrs = wrap
   "<trk> <trkseg> \n\
   \<trkpt lat=\"51\" lon=\"-0.1\"> \n\
   \ <ele>25.2</ele>\n\