Add type signatures and extension in code

Fixes #71

Database/MongoDB.hs

@@ -1,42 +1,54 @@
-{- |
-Client interface to MongoDB database management system.
-
-Simple example below. Use with language extensions /OverloadedStrings/ & /ExtendedDefaultRules/.
-
-
-> import Database.MongoDB
-> import Control.Monad.Trans (liftIO)
->
-> main = do
->    pipe <- connect (host "127.0.0.1")
->    e <- access pipe master "baseball" run
->    close pipe
->    print e
->
-> run = do
->    clearTeams
->    insertTeams
->    allTeams >>= printDocs "All Teams"
->    nationalLeagueTeams >>= printDocs "National League Teams"
->    newYorkTeams >>= printDocs "New York Teams"
->
-> clearTeams = delete (select [] "team")
->
-> insertTeams = insertMany "team" [
->    ["name" =: "Yankees", "home" =: ["city" =: "New York", "state" =: "NY"], "league" =: "American"],
->    ["name" =: "Mets", "home" =: ["city" =: "New York", "state" =: "NY"], "league" =: "National"],
->    ["name" =: "Phillies", "home" =: ["city" =: "Philadelphia", "state" =: "PA"], "league" =: "National"],
->    ["name" =: "Red Sox", "home" =: ["city" =: "Boston", "state" =: "MA"], "league" =: "American"] ]
->
-> allTeams = rest =<< find (select [] "team") {sort = ["home.city" =: 1]}
->
-> nationalLeagueTeams = rest =<< find (select ["league" =: "National"] "team")
->
-> newYorkTeams = rest =<< find (select ["home.state" =: "NY"] "team") {project = ["name" =: 1, "league" =: 1]}
->
-> printDocs title docs = liftIO $ putStrLn title >> mapM_ (print . exclude ["_id"]) docs
->
--}
+-- |
+-- Client interface to MongoDB database management system.
+--
+-- Simple example below. 
+--
+-- @
+-- {\-\# LANGUAGE OverloadedStrings \#\-}
+-- {\-\# LANGUAGE ExtendedDefaultRules \#\-}
+-- 
+-- import Database.MongoDB
+-- import Control.Monad.Trans (liftIO)
+-- 
+-- main :: IO ()
+-- main = do
+--    pipe <- connect (host \"127.0.0.1\")
+--    e <- access pipe master \"baseball\" run
+--    close pipe
+--    print e
+-- 
+-- run :: Action IO ()
+-- run = do
+--    clearTeams
+--    insertTeams
+--    allTeams >>= printDocs \"All Teams\"
+--    nationalLeagueTeams >>= printDocs \"National League Teams\"
+--    newYorkTeams >>= printDocs \"New York Teams\"
+-- 
+-- clearTeams :: Action IO ()
+-- clearTeams = delete (select [] \"team\")
+-- 
+-- insertTeams :: Action IO [Value]
+-- insertTeams = insertMany \"team\" [
+--    [\"name\" =: \"Yankees\", \"home\" =: [\"city\" =: \"New York\", \"state\" =: \"NY\"], \"league\" =: \"American\"],
+--    [\"name\" =: \"Mets\", \"home\" =: [\"city\" =: \"New York\", \"state\" =: \"NY\"], \"league\" =: \"National\"],
+--    [\"name\" =: \"Phillies\", \"home\" =: [\"city\" =: \"Philadelphia\", \"state\" =: \"PA\"], \"league\" =: \"National\"],
+--    [\"name\" =: \"Red Sox\", \"home\" =: [\"city\" =: \"Boston\", \"state\" =: \"MA\"], \"league\" =: \"American\"] ]
+-- 
+-- allTeams :: Action IO [Document]
+-- allTeams = rest =<< find (select [] \"team\") {sort = [\"home.city\" =: 1]}
+-- 
+-- nationalLeagueTeams :: Action IO [Document]
+-- nationalLeagueTeams = rest =<< find (select [\"league\" =: \"National\"] \"team\")
+-- 
+-- newYorkTeams :: Action IO [Document]
+-- newYorkTeams = rest =<< find (select [\"home.state\" =: \"NY\"] \"team\") {project = [\"name\" =: 1, \"league\" =: 1]}
+-- 
+-- printDocs :: String -> [Document] -> Action IO ()
+-- printDocs title docs = liftIO $ putStrLn title >> mapM_ (print . exclude [\"_id\"]) docs
+--
+-- @
+--
 
 module Database.MongoDB (
     module Data.Bson,