diff --git a/HLearn-distributions.cabal b/HLearn-distributions.cabal
--- a/HLearn-distributions.cabal
+++ b/HLearn-distributions.cabal
@@ -1,5 +1,5 @@
 Name:                HLearn-distributions
-Version:             0.1.0.1
+Version:             0.2.1
 Synopsis:            Distributions for use with the HLearn library
 Description:         This module is used to estimate statistical distributions from data.  The focus is a clean interface inspired by algebra.
 Category:            Data Mining, Machine Learning, Statistics
diff --git a/src/HLearn/Gnuplot/Distributions.hs b/src/HLearn/Gnuplot/Distributions.hs
--- a/src/HLearn/Gnuplot/Distributions.hs
+++ b/src/HLearn/Gnuplot/Distributions.hs
@@ -10,6 +10,7 @@
 import HLearn.Algebra
 import HLearn.Models.Distributions
 
+import qualified Data.Map as Map
 import qualified Data.Vector.Unboxed as VU
 
 import Control.Monad
@@ -20,62 +21,113 @@
     { dataFile :: FilePath
     , gnuFile :: FilePath
     , picFile :: FilePath
-    , plotPoints :: [Double]
     }
 
-class PlottableDistribution dist where
-    genPlotPoints :: dist -> [Double]
-
-instance PlottableDistribution (KDE Double) where
-    genPlotPoints (SGJust kde) = VU.toList $ samplePoints $ params kde
-
-genPlotParams :: (PlottableDistribution dist) => String -> dist -> PlotParams
-genPlotParams str dist = PlotParams
+plotFile :: String -> PlotParams
+plotFile str = PlotParams
     { dataFile = str++".dat"
     , gnuFile  = str++".gnu"
     , picFile  = str++".ps"
-    , plotPoints = genPlotPoints dist
     }
 
+-- | provided due to backwards compatibility with the nuclear weapons blog post.
+genPlotParams :: String -> a -> PlotParams
+genPlotParams str a = plotFile str
+
 defPlotParams = PlotParams
     { dataFile = "hlearn-distributions.dat"
     , gnuFile = "hlearn-distributions.gnu"
     , picFile = "hlearn-distributions.ps"
-    , plotPoints = [-5..5]
     }
-    
-plotDistribution :: (Distribution dist Double Double) => PlotParams -> dist -> IO ()
-plotDistribution params dist = do
-    
-    -- Create data file
-    putStrLn "Creating data file..."
-    datah <- openFile (dataFile params) WriteMode
-    forM_ (plotPoints params) $ \x -> do
---     forM_ (map (/10) [-50..50]) $ \x -> do
-        hPutStrLn datah $ show (x::Double) ++ " " ++ show (pdf dist x::Double)
-    hClose datah
-    
-    -- Create gnuplot file
-    putStrLn "Plotting data"
-    gnuh <- openFile (gnuFile params) WriteMode
-    hPutStrLn gnuh $ "set terminal postscript \"Times-Roman\" 25"
-    hPutStrLn gnuh $ "set output \"" ++ (picFile params) ++ "\""
-    hPutStrLn gnuh $ "unset xtics; unset ytics; unset key"
-    hPutStrLn gnuh $ "set border 0; set xzeroaxis lt 1; set yzeroaxis lt 1"
-    hPutStrLn gnuh $ "plot '"++(dataFile params)++"' using 1:2 lt 1 lw 4 lc rgb '#ccccff' with filledcurves, \\"
-    hPutStrLn gnuh $ "     '"++(dataFile params)++"' using 1:2 lt 1 lw 4 lc rgb '#0000ff' with lines"
-    hClose gnuh
+
+class PlottableDistribution dist where
+    plotDistribution :: PlotParams -> dist -> IO ()
+    plotDistribution params dist = do
+        -- Create data file
+        putStrLn "Creating data file..."
+        datah <- openFile (dataFile params) WriteMode
+        hPutStrLn datah $ plotdata dist
+        hClose datah
+        
+        -- Create gnuplot file
+        putStrLn "Plotting data"
+        gnuh <- openFile (gnuFile params) WriteMode
+        hPutStrLn gnuh $ gnuplot params dist
+        hClose gnuh
+        
+        -- Run gnuplot, creating picture
+        system $ "gnuplot "++(gnuFile params)
+        putStrLn "done."
+        return ()
+
+    plotdata :: dist -> String
+    gnuplot  :: PlotParams -> dist -> String
     
-    -- Run gnuplot, creating picture
-    system $ "gnuplot "++(gnuFile params)
-    putStrLn "done."
-    return ()
+instance PlottableDistribution (KDE Double) where
+    plotdata dist@(SGJust kde) = mconcat [show (x::Double) ++ " " ++ show (pdf dist x::Double) | x <- plotPoints]
+        where
+            plotPoints = VU.toList $ samplePoints $ params kde
+
+    gnuplot params dist
+        =  "set terminal postscript \"Times-Roman\" 25"
+        ++ "set output \"" ++ (picFile params) ++ "\""
+        ++ "unset xtics; unset ytics; unset key"
+        ++ "set border 0; set xzeroaxis lt 1; set yzeroaxis lt 1"
+        ++ "plot '"++(dataFile params)++"' using 1:2 lt 1 lw 4 lc rgb '#ccccff' with filledcurves, \\"
+        ++ "     '"++(dataFile params)++"' using 1:2 lt 1 lw 4 lc rgb '#0000ff' with lines"
+        
+instance (Show label, Show prob, Num prob, Ord prob) => PlottableDistribution (Categorical label prob) where
+    plotdata dist@(Categorical pdf) = concat $ do
+        (label,prob) <- Map.toList pdf
+        return $ show label++" "++show prob++"\n"
+        
+    gnuplot params (Categorical pdf)
+        = "set terminal postscript \"Times-Roman\" 25; set output \""++ (picFile params) ++ "\"\n"
+        ++"set tics scale 0; set xtics nomirror; unset ytics; unset key\n"
+        ++"set border 2; set xzeroaxis lt 1\n"
+        ++"set ylabel \"Probability\"\n"
+        ++yrange
+        ++"set style fill border -1\n"
+        ++"set style data histogram; set style histogram cluster gap 1\n"
+        ++"plot '"++(dataFile params)++"' using 2:xticlabels(1)\n"
+        where
+            positiveSamples = or $ map (\(k,v) -> v>0) $ Map.toList pdf
+            negativeSamples = or $ map (\(k,v) -> v<0) $ Map.toList pdf
+            yrange = if positiveSamples && negativeSamples
+                then ""
+                else if positiveSamples
+                    then "set yrange [0:]\n"
+                    else "set yrange [:0]\n"
+{-        =  "set terminal postscript \"Times-Roman\" 25 \n"
+        ++ "set output \"" ++ (picFile params) ++ "\" \n"
+        ++ "unset xtics; unset ytics; unset key\n"
+        ++ "set border 0; set xzeroaxis lt 1; set yzeroaxis lt 1\n"
+        ++ "set style data histogram \n"
+        ++ "plot '"++(dataFile params)++"' using 1:2 \n"-}
     
--- testL = [1,1.1,1.2,0,5,-3,2,1,2.5,2.9::Double]
--- kde = train' (KDEParams 1 (VU.fromList $ map (/10) [-50..50::Double]) (KernelBox Gaussian)) testL :: KDE Double
--- 
--- pdfL = sequence_ $ do
---     x <- map (/10) [-50..50]
---     let y = pdf kde x :: Double
---     seq y (return ())
---     return $ putStrLn $ (show (x::Double)) ++ " " ++ show y
+-- plotDistribution :: (Distribution dist Double Double) => PlotParams -> dist -> IO ()
+-- plotDistribution params dist = do
+--     
+--     -- Create data file
+--     putStrLn "Creating data file..."
+--     datah <- openFile (dataFile params) WriteMode
+--     forM_ (plotPoints params) $ \x -> do
+-- --     forM_ (map (/10) [-50..50]) $ \x -> do
+--         hPutStrLn datah $ show (x::Double) ++ " " ++ show (pdf dist x::Double)
+--     hClose datah
+--     
+--     -- Create gnuplot file
+--     putStrLn "Plotting data"
+--     gnuh <- openFile (gnuFile params) WriteMode
+--     hPutStrLn gnuh $ "set terminal postscript \"Times-Roman\" 25"
+--     hPutStrLn gnuh $ "set output \"" ++ (picFile params) ++ "\""
+--     hPutStrLn gnuh $ "unset xtics; unset ytics; unset key"
+--     hPutStrLn gnuh $ "set border 0; set xzeroaxis lt 1; set yzeroaxis lt 1"
+--     hPutStrLn gnuh $ "plot '"++(dataFile params)++"' using 1:2 lt 1 lw 4 lc rgb '#ccccff' with filledcurves, \\"
+--     hPutStrLn gnuh $ "     '"++(dataFile params)++"' using 1:2 lt 1 lw 4 lc rgb '#0000ff' with lines"
+--     hClose gnuh
+--     
+--     -- Run gnuplot, creating picture
+--     system $ "gnuplot "++(gnuFile params)
+--     putStrLn "done."
+--     return ()
diff --git a/src/HLearn/Models/Distributions/Categorical.hs b/src/HLearn/Models/Distributions/Categorical.hs
--- a/src/HLearn/Models/Distributions/Categorical.hs
+++ b/src/HLearn/Models/Distributions/Categorical.hs
@@ -44,8 +44,8 @@
 instance Model CategoricalParams (Categorical label probtype) where
     getparams model = CategoricalParams
 
--- instance DefaultModel CategoricalParams (Categorical label probtype) where
-instance DefaultModel CategoricalParams (Categorical Int Double) where
+instance DefaultModel CategoricalParams (Categorical label probtype) where
+-- instance DefaultModel CategoricalParams (Categorical Int Double) where
     defparams = CategoricalParams
 
 -------------------------------------------------------------------------------
@@ -69,10 +69,10 @@
 -------------------------------------------------------------------------------
 -- Distribution
 
-instance (Ord label, Ord prob, Floating prob, Random prob) => Distribution (Categorical label prob) label prob where
+instance (Ord label, Ord prob, Fractional prob, Random prob) => Distribution (Categorical label prob) label prob where
 
     {-# INLINE pdf #-}
-    pdf dist label = 0.0001+(val/tot)
+    pdf dist label = {-0.0001+-}(val/tot)
         where
             val = case Map.lookup label (pdfmap dist) of
                 Nothing -> 0
diff --git a/src/HLearn/Models/Distributions/Common.hs b/src/HLearn/Models/Distributions/Common.hs
--- a/src/HLearn/Models/Distributions/Common.hs
+++ b/src/HLearn/Models/Distributions/Common.hs
@@ -12,7 +12,7 @@
 -- Distribution
     
 -- | We use the same class for both discrete and continuous distributions.  Unfortunately, we cannot use the type classes from the 'statistics' package because we require more generalilty.
-class Distribution dist dp prob | dist -> dp where
+class Distribution dist dp prob | dist -> dp, dist -> prob where
     pdf :: dist -> dp -> prob 
 --     cdf :: dist -> dp -> prob 
 --     cdfInverse :: dist -> prob -> dp