diff --git a/Graphics/Diagrams/Backend/SVGTree.hs b/Graphics/Diagrams/Backend/SVGTree.hs
--- a/Graphics/Diagrams/Backend/SVGTree.hs
+++ b/Graphics/Diagrams/Backend/SVGTree.hs
@@ -3,15 +3,25 @@
 module Graphics.Diagrams.Backend.SVGTree (renderDiagram, saveDiagram, SvgDiagram) where
 
 import Graphics.Diagrams.Core as D
-import Prelude hiding (sum,mapM_,mapM,concatMap)
-import Graphics.Svg as S
+import Prelude hiding (sum,mapM_,mapM,concatMap,Num(..),(/))
+import qualified Prelude
+import Graphics.Svg as S hiding (Group)
 import Control.Monad.RWS
 import Linear.V2 (V2(..))
 import Codec.Picture.Types (PixelRGBA8(..))
 import Graphics.Text.TrueType
 import qualified Data.Vector.Unboxed as V
 import qualified Data.Map as M
+import Algebra.Classes
 
+instance Additive a => Additive (V2 a) where
+  a + b = (+) <$> a <*> b
+  zero = pure zero
+
+instance Group a => Group (V2 a) where
+  a - b = (-) <$> a <*> b
+  negate = fmap negate
+
 -- TODO -- add a newtype so this does not leak to the user code.
 type SvgM = RWS Font [Path] (V2 Double,V2 Double)
 
@@ -65,8 +75,8 @@
         V2 hi'x hi'y = hi + border
         border = V2 5 5
 
-ptToPx :: forall a. Fractional a => a -> a
-ptToPx z = 4*z / 3
+ptToPx :: forall a. Field a => a -> a
+ptToPx z = fromInteger 4*z / fromInteger 3
 
 renderPoint :: FrozenPoint -> V2 Double
 renderPoint (D.Point x y) = V2 (ptToPx x) (negate $ ptToPx y)
diff --git a/Setup.hs b/Setup.hs
--- a/Setup.hs
+++ b/Setup.hs
@@ -1,2 +1,4 @@
+#!/usr/bin/env runhaskell
 import Distribution.Simple
+main :: IO ()
 main = defaultMain
diff --git a/examples/Main.hs b/examples/Main.hs
--- a/examples/Main.hs
+++ b/examples/Main.hs
@@ -1,41 +1,45 @@
 import Graphics.Diagrams.SVG
-
+import Algebra.Classes
+import Prelude hiding (Num(..))
 -- autoLab s i = do
---   o <- labelObj s
+--   o <- label s
 --   -- stroke "red" $ path $ polyline [o # BaseW, o # BaseE]
 --   -- stroke "blue" $ path $ polygon [o # NW, o # NE, o # SE, o # SW]
 --   autoLabelObj o i
 
-autoLab = autoLabel
+label' x = label x x
+autoLabel' x = autoLabel x x
 
 testDiagram :: SvgDiagram ()
 testDiagram = do
-  -- draw $ path $ circle (Point 0 0) 5
-  a   <- labelObj $ "ha"
-  b   <- labelObj $ "b"
-  a'  <- draw $ circleShape -- labelObj $ ensureMath $ "c"
-  width a' === 15
-  b'  <- labelObj $ "b'"
-  a'' <- labelObj $ "."
-  b'' <- labelObj $ "."
+  noOverlap =<< label' "whatever1"
+  noOverlap =<< label' "whatever2"
+  -- noOverlap =<< label' "whatever3"
+  -- noOverlap =<< label' "whatever4"
+  a   <- label' $ "ha"
 
-  -- c <- texObj $ ensureMath $ "c"
-  -- Center ▸ c === MP.center [E ▸ a'', E ▸ b''] + (20 +: 0)
+  b   <- label' $ "b"
+  a'  <- draw $ circle "circleEx" -- label $ ensureMath $ "c"
+  width a' === constant 15
+  b'  <- label' $ "b'"
+  a'' <- label' $ "."
+  b'' <- label' $ "."
 
-  let width = 70
-  vdist b a === 30
+  let width = constant 70
+  vdist b a === constant 30
   hdist a a' === width
   hdist a' a'' === width
   alignMatrix $ map (map (#Center)) $ [[a,a',a'']
                                       ,[b, b',b'']]
-  autoLab "aa'" =<< arrow a a'
-  autoLab "bb'" =<< arrow b b'
-  autoLab "ab" . turn180 =<< arrow a b
-  autoLab "a'a''" =<< arrow a' a''
-  autoLab "b'b''" =<< arrow b' b''
+  noOverlap =<< autoLabel' "aa'" =<< arrow a a'
+  noOverlap =<< autoLabel' "bb'" =<< arrow b b'
+  noOverlap =<< autoLabel' "ab" . turn180 =<< arrow a b
+  noOverlap =<< autoLabel' "a'a''" =<< arrow a' a''
+  noOverlap =<< autoLabel' "b'b''" =<< arrow b' b''
 
+
   draw $ do
-    autoLab "equal" =<< edge a'' b''
+    autoLabel' "equal" =<< edge a'' b''
   return ()
 
 main :: IO ()
diff --git a/lp-diagrams-svg.cabal b/lp-diagrams-svg.cabal
--- a/lp-diagrams-svg.cabal
+++ b/lp-diagrams-svg.cabal
@@ -1,14 +1,20 @@
 name:           lp-diagrams-svg
-version:        1.0
+version:        1.1
 category:       Graphics
 synopsis:       SVG Backend for lp-diagrams
-license:        AGPL-3
+license:        GPL
 license-file:   LICENSE
 author:         Jean-Philippe Bernardy
 maintainer:     jeanphilippe.bernardy@gmail.com
 Cabal-Version:  >= 1.18
 build-type:     Simple
+description:
+  SVG backend for lp-diagrams
 
+source-repository head
+  type: git
+  location: https://github.com/jyp/lp-diagrams-svg
+
 Flag example
   Description: Compile example.
   manual: True
@@ -29,6 +35,7 @@
                , FontyFruity
                , vector
                , optparse-applicative
+               , gasp
   exposed-modules: Graphics.Diagrams.Backend.SVGTree
   exposed-modules: Graphics.Diagrams.SVG
 
@@ -48,6 +55,7 @@
                , containers
                , lens
                , FontyFruity
+               , gasp
                -- , svg-tree
                -- , mtl
                -- , linear