Example.hs

import Data.HMap

-- type can be inferred.
example :: HKey x String -> HKey x1 Double -> HKey x2 Bool
            -> String
example name salary female =
   format a ++ "\n" ++ format b ++ "\n"
   where a = insert name "Edsger" $
             insert salary 4450.0 $
             insert female False empty
         b = insert name "Ada"    $
             insert salary 5000.0 $
             insert female True empty
         format x = x ! name ++
                    ": salary=" ++ show (x ! salary) ++
                    ", female="  ++ show (x ! female)

keyLocal :: String
keyLocal = withKey $ withKey $ withKey example

keyGlobal :: IO String
keyGlobal =
  do name   <- createKey
     salary <- createKey
     female <- createKey
     return $ example name salary female

main = do print "local"
          putStr keyLocal
          print "global"
          keyGlobal >>= putStr