This library has 2 high level functions

• cursorPipe to stream a query from postgres DB
• connect to handle connection in 'SafeT IO'

Here is how usage looks like from a production excerpt for a table of samples

mkDB :: ByteString mkDB = [qmb| create table samples ( id uuid not null, time bigint not null, value double precision not null, ); |] @ streamSamples :: RunSession -> Int64 -- ^ first sample time -> Producer (UUID, Int64, Double) (SafeT IO) () streamSamples (RunSession run) from' = yield from' >-> cursorPipe do run do samplesEncoder do samplesDecoder do Cursor "sample_cursor" do Template [qmb| select * from samples where time >= $1 order by time; |] do 1000

samplesEncoder :: Params Int64 samplesEncoder = param $ E.nonNullable E.int8

samplesDecoder :: Row (UUID, Int64, Double) samplesDecoder = (,,) $ do column . D.nonNullable $ D.uuid * do column . D.nonNullable $ D.int8 * do column . D.nonNullable $ D.float8

localConnect :: Trace IO DatabaseLog -> SafeT IO RunSession localConnect tracer = do connect tracer $ settings "10.1.9.95" 5432 "postgres" "postgres" "postgres"

main :: IO () main = do ts <- getPOSIXTime runSafeT $ do run' <- localConnect pPrint runEffect $ streamSamples run' (floor ts - 600) >-> P.print

@