runConnectionPool :: MonadControlIO m => SqlPersist m a -> ConnectionPool -> m a
runConnectionPool = runSqlPool

withConnectionPool :: MonadControlIO m => AppConfig -> (ConnectionPool -> m a) -> m a
withConnectionPool conf f = do
    cs <- liftIO $ loadConnStr (appEnv conf)
    with~upper~Pool cs (connectionPoolSize conf) f
  where
    -- | The database connection string. The meaning of this string is backend-
    -- specific.
    loadConnStr :: AppEnvironment -> IO Text
    loadConnStr env = do
        allSettings <- (join $ YAML.decodeFile ("config/~backendLower~.yml" :: String)) >>= fromMapping
        settings <- lookupMapping (show env) allSettings
        database <- lookupScalar "database" settings :: IO Text

        connPart <- fmap concat $ (flip mapM) ["user", "password", "host", "port"] $ \key -> do
          value <- lookupScalar key settings
          return $ [st| #{key}=#{value} |]
        return $ [st|#{connPart} dbname=#{database}|]

-- Example of making a dynamic configuration static
-- use /return $(mkConnStr Production)/ instead of loadConnStr
-- mkConnStr :: AppEnvironment -> Q Exp
-- mkConnStr env = qRunIO (loadConnStr env) >>= return . LitE . StringL