diff --git a/Maaps.cabal b/Maaps.cabal
index 13040a2..b6aae38 100644
--- a/Maaps.cabal
+++ b/Maaps.cabal
@@ -29,6 +29,7 @@ library
                      , biocore
                      , fixed-list
                      , QuickCheck
+                     , safe
   default-language:    Haskell2010
 
 executable Maaps-exe
diff --git a/src/VcfMerge.hs b/src/VcfMerge.hs
new file mode 100644
index 0000000..0a71d6f
--- /dev/null
+++ b/src/VcfMerge.hs
@@ -0,0 +1,112 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE DataKinds         #-}  -- last three for Options
+{-# LANGUAGE TypeOperators     #-}
+{-# LANGUAGE DeriveGeneric #-}
+
+import Safe (atMay, headMay, lastMay, readMay, tailMay)
+import Data.Maybe (catMaybes, fromMaybe)
+import qualified Data.Text as T
+import qualified Data.Text.IO as T
+import Data.Text (Text())
+import Data.List (find, groupBy, group)
+import Control.Monad (when)
+import Options.Generic
+
+--pos :: Text -> Int
+--pos s = fromMaybe (-1) (toInt =<< (nth 1 $ T.splitOn "\t" s))
+data Options = Options {   maaps :: FilePath <?> "Tab delimited MAAPs output"
+                         , vcf :: FilePath <?> "VCF ouptut of ngsmapper." }
+  deriving (Generic, Show)
+instance ParseRecord Options
+
+toInt x = readMay $ T.unpack x :: Maybe Int
+nth = flip atMay
+readNuc x = readMay $ T.unpack x :: Maybe Nucleotide
+data Nucleotide = A | T | C | G | (*)
+  deriving (Show, Eq, Read)
+
+
+data Stats = Stats { dp :: Int, alts :: [Nucleotide], pacs :: [Int], pos :: Int, ref :: Text }
+  deriving (Show, Eq)
+--
+formatStats Stats {dp=dp', alts=alts', pacs=pacs', pos=_, ref=ref'} = s where
+  s = T.intercalate "\t" [(tshow dp'), showAlts alts' pacs', ref'] 
+  showAlts :: [Nucleotide] -> [Int] -> Text
+  showAlts [] [] = "."
+  showAlts xs ys = T.intercalate "," $ zipWith (\x y -> (tshow x) `T.append` "==" `T.append` (tshow y)) xs ys
+ 
+tshow :: (Show a) => a -> Text
+tshow = T.pack . show
+--
+--T
+s = "Den4/KDH0146A/Thailand/Unk/Den4_1\t6\t.\tA\tG,C,T\t.\t.\tDP=2998;RC=2973;RAQ=37;PRC=99;AC=1,10,14;AAQ=37,37,37;PAC=3,2,1;CBD=2973;CB=A;HPOLY"
+
+byRef xs = groupBy (\x y -> (headMay x) == (headMay y)) xs
+
+readMaaps = filter (\x -> length x > 1) . map T.words . tail . T.lines 
+-- note that ngs_mapper vcfs have an entry for every position, even if there are no ALTs there. so suck!
+--readVCF = catMaybes . map parseInfo . dropWhile (T.isPrefixOf "#") . T.lines
+readVCF :: Text -> [Stats]
+readVCF x = fromMaybe (error "Failed to parse vcf file.") $ traverse parseInfo $ dropWhile (T.isPrefixOf "#") $ T.lines x
+main = do
+  opts <- (getRecord "Starting maaps" :: IO Options)
+  let vcf' = unHelpful $ vcf opts
+  let tsv  = unHelpful $ maaps opts
+  stats <- readVCF   <$> T.readFile vcf'
+  maaps <- readMaaps <$> T.readFile tsv
+  maapsHeader <- head <$> T.lines <$> T.readFile tsv
+  let header = maapsHeader `T.append` "\tDP\tAlts\tRef"
+  putStrLn $ T.unpack header
+  putStrLn $ process stats maaps
+
+process ms ss = T.unpack $ T.unlines $ map (uncurry output) $ joinMaapsStats ms ss
+
+
+--output :: Maybe ([Text], Stats) -> String
+output :: [Text] -> Maybe Stats -> Text
+output mr (Just stats) = (T.intercalate "\t" mr) `T.append` "\t" `T.append` (formatStats stats)
+output mr Nothing      = T.intercalate "\t" (mr ++ ["-", "-"])
+
+joinMaapsStats :: [Stats] -> [[Text]] -> [([Text], Maybe Stats)]
+joinMaapsStats vcf maaps = map (\m -> (m, find (matcher m) vcf)) maaps
+  where matcher = if (length $ group $ fmap ref vcf) == 1 then matchPos else matchBoth
+--  f m = do
+--    r <- find (match m) tsvs
+--    return (r, m)
+--matchPos x y = (toInt =<< nth 2 x) == (Just $ pos y)
+matchPos :: [Text] -> Stats -> Bool
+matchPos x y = (read $ T.unpack  (x !! 2)) == (pos y)
+matchBoth :: [Text] -> Stats -> Bool
+matchBoth x y = ((ref'  x) == (ref y)) && matchPos x y
+--ref' x = T.tail <$> snd <$> T.breakOn "_" <$> headMay x
+ref' x = T.tail $ snd $ T.breakOn "_" $ head x
+
+   
+--groupBy (\x y -> ( (pos y)) 
+---- get DP; then depending on number of alts, expect and get that number of PAC (note PAC may be zero)
+-- | hey
+-- >>> parseInfo s
+-- Just (Stats {dp = 2998, alts = [G,C,T], pacs = [3,2,1]}) 
+parseInfo :: Text -> Maybe Stats
+parseInfo line = do
+  info <- lastMay cols
+  let fields = T.splitOn ";" info
+  dp'  <- toInt =<< fieldValue "DP" fields
+  rawAlts' <- T.splitOn "," <$> nth 4 cols
+  let altsMaybe' = mapM readNuc rawAlts' -- note mapM = sequence . map
+  let pacMaybe' = mapM toInt =<< T.splitOn "," <$> fieldValue "PAC" fields
+  let pacs' = fromMaybe [] pacMaybe'  :: [Int]
+  let alts' = fromMaybe [] altsMaybe'
+  --pacs' <- sequence $ map toInt $ T.splitOn "," pac' 
+  pos'  <- toInt =<< nth 1 cols
+  ref'  <- nth 0 $ T.splitOn "\t" line
+  if (length alts' == length pacs') then
+    return $ Stats { dp = dp', alts = alts', pacs = pacs', pos = pos', ref = ref'}
+    else Nothing
+  where 
+    cols   = T.splitOn "\t" line
+    fieldValue pre xs = nth 1 =<< T.splitOn "=" <$> find (T.isPrefixOf pre) xs
+
+-- output as TSV, then join with MAAPs output on CHROM and POS
+
+--main = putStrLn $ show $ parseInfo s