Opaleye + resource-pool + postgresql-simple

Foobar.hs

-- | Simple alias for PostgreSQL connection pools.
type PostgresPool = Pool.Pool PGS.Connection

-- | Execute a query against the PostgreSQL database, using
-- a connection pool.
runQueryPool :: Default QueryRunner cols vals
             => Pool.Pool PGS.Connection
             -> Query cols
             -> IO [vals]
runQueryPool p q = Pool.withResource p (`runQuery` q)

-- | Create a @'PostgresPool'@ connection pool.
createPostgresPool :: Maybe PGS.ConnectInfo
                   -- ^ Optional connection information.
                   -> Int
                   -- ^ Number of stripes.
                   -> Time.NominalDiffTime
                   -- ^ Time to keep unused connections open.
                   -> Int
                   -- ^ Maximum connections per stripe.
                   -> IO PostgresPool
createPostgresPool connInfo = go where
  go   = Pool.createPool (PGS.connectPostgreSQL info) PGS.close
  info = PGS.postgreSQLConnectionString
       $ fromMaybe PGS.defaultConnectInfo connInfo

Thanks!