diff --git a/diversity.cabal b/diversity.cabal
--- a/diversity.cabal
+++ b/diversity.cabal
@@ -2,14 +2,14 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                diversity
-version:             0.8.0.2
+version:             0.8.1.0
 synopsis:            Quantify the diversity of a population
 description:         Find the diversity of a collection of entities, mainly for use with fasta sequences.
 homepage:            https://github.com/GregorySchwartz/diversity
 license:             GPL-3
 license-file:        LICENSE
 author:              Gregory W. Schwartz
-maintainer:          gregory.schwartz@drexel.edu
+maintainer:          gsch@mail.med.upenn.edu
 -- copyright:           
 category:            Bioinformatics
 build-type:          Simple
diff --git a/src/src-exec/Main.hs b/src/src-exec/Main.hs
--- a/src/src-exec/Main.hs
+++ b/src/src-exec/Main.hs
@@ -27,7 +27,7 @@
 data Options = Options { inputLabel             :: String
                        , inputOrder             :: Double
                        , inputWindow            :: Int
-                       , inputFasta             :: String
+                       , inputFasta             :: Maybe String
                        , inputSampleField       :: Int
                        , inputCountField        :: Int
                        , inputSubsampling       :: String
@@ -59,21 +59,21 @@
       <*> option auto
           ( long "input-order"
          <> short 'r'
-         <> metavar "[1]|INT"
+         <> metavar "[1] | INT"
          <> value 1
          <> help "The order of true diversity" )
       <*> option auto
           ( long "input-window"
          <> short 'w'
-         <> metavar "[1]|INT"
+         <> metavar "[1] | INT"
          <> value 1
          <> help "The length of the sliding window for generating fragments" )
-      <*> strOption
+      <*> optional ( strOption
           ( long "input-fasta"
          <> short 'i'
-         <> metavar "FILE"
-         <> value ""
+         <> metavar "[Nothing] | FILE"
          <> help "The fasta file containing the germlines and clones" )
+        )
       <*> option auto
           ( long "input-sample-field"
          <> short 'S'
@@ -166,7 +166,9 @@
           ( long "std"
          <> short 't'
          <> help "Whether to output to stdout or to a file if no file is\
-                 \ supplied" )
+                 \ supplied. Must still put some string in -O, -c, or -o\
+                 \ depending on which output is needed."
+          )
       <*> strOption
           ( long "output-rarefaction"
          <> short 'O'
@@ -199,9 +201,9 @@
 
 pipesPositionMap :: Options -> IO PositionMap
 pipesPositionMap opts = do
-    h <- if null . inputFasta $ opts
-            then return IO.stdin
-            else IO.openFile (inputFasta opts) IO.ReadMode
+    h <- case inputFasta opts of
+            Nothing  -> return IO.stdin
+            (Just x) -> IO.openFile x IO.ReadMode
     runEffect
           $ P.fold (Map.unionWith (Map.unionWith (+))) Map.empty id
           $ P.fromHandle h
@@ -266,4 +268,4 @@
   where
     opts = info (helper <*> options)
       ( fullDesc
-     <> progDesc "Quantify the diversity of a population" )
+     <> progDesc "Quantify the diversity of a population." )
diff --git a/src/src-lib/Math/Diversity/Diversity.hs b/src/src-lib/Math/Diversity/Diversity.hs
--- a/src/src-lib/Math/Diversity/Diversity.hs
+++ b/src/src-lib/Math/Diversity/Diversity.hs
@@ -10,6 +10,7 @@
                                 , richness
                                 , diversity
                                 , diversityOfMap
+                                , diversityOfMapWithContribution
                                 , chao1
                                 , chao2
                                 , chao1Var
@@ -84,6 +85,33 @@
                  . Map.map ( \x -> p_i x * log (p_i x))
     p_i x        = fromIntegral x / fromIntegral (Map.foldl' (+) 0 sample)
 
+-- | Returns the diversity of a map of the species and how many times it
+-- appears, along with the contribution of each species.
+diversityOfMapWithContribution
+    :: (Ord a)
+    => Double -> Map.Map a Int -> (Double, Map.Map a Double)
+diversityOfMapWithContribution order sample
+    | Map.null sample    = (0, Map.empty)
+    | order == 1         = (exp . h $ sample, contrib)
+    | otherwise          = ( ( Map.foldl' (+) 0
+                             . Map.map ((** order) . p_i)
+                             $ sample
+                             )
+                          ** pow
+                           , contrib
+                           )
+  where
+    contrib      = Map.map
+                    ( (/ (fromIntegral $ Map.foldl' (+) 0 sample))
+                    . fromIntegral
+                    )
+                    sample
+    pow          = 1 / (1 - order)
+    h            = negate
+                 . Map.foldl' (+) 0
+                 . Map.map ( \x -> p_i x * log (p_i x))
+    p_i x        = fromIntegral x / fromIntegral (Map.foldl' (+) 0 sample)
+
 -- | Returns the richness of the observed data
 richness :: (Ord a, Ord b) => Map.Map (a, b) c -> Int
 richness = Map.size . Map.mapKeys snd
@@ -323,4 +351,3 @@
                           (fromIntegral x)
                           1
                           (fromIntegral x)
-