{-# LANGUAGE OverloadedStrings #-}

module Hasql.Private.CursorTransactionIO where

-- bytestring
import Data.ByteString (ByteString)

-- bytestring-tree-builder
import ByteString.TreeBuilder

-- transformers
import Control.Monad.Error.Class

-- mtl
import Control.Monad.Reader
import Control.Monad.State

-- unliftio-core
import Control.Monad.IO.Unlift

-- resourcet
import Control.Monad.Trans.Resource

-- hasql
import Hasql.Encoders (noParams)
import Hasql.Decoders (Result, noResult)
import Hasql.Session hiding (statement)
import Hasql.Statement

-- hasql-streaming
import Hasql.Private.Session.UnliftIO
import Hasql.TransactionIO hiding (statement)
import qualified Hasql.TransactionIO as TransactionIO

-- | A PostgresSQL cursor that produces results of type @a@ when fetched
data Cursor s a = Cursor 
  { forall s a. Cursor s a -> ByteString
cursorVar :: ByteString
  , forall s a. Cursor s a -> Result a
decoder :: Result a
  }
  deriving ((forall a b. (a -> b) -> Cursor s a -> Cursor s b)
-> (forall a b. a -> Cursor s b -> Cursor s a)
-> Functor (Cursor s)
forall a b. a -> Cursor s b -> Cursor s a
forall a b. (a -> b) -> Cursor s a -> Cursor s b
forall s a b. a -> Cursor s b -> Cursor s a
forall s a b. (a -> b) -> Cursor s a -> Cursor s b
forall (f :: * -> *).
(forall a b. (a -> b) -> f a -> f b)
-> (forall a b. a -> f b -> f a) -> Functor f
$cfmap :: forall s a b. (a -> b) -> Cursor s a -> Cursor s b
fmap :: forall a b. (a -> b) -> Cursor s a -> Cursor s b
$c<$ :: forall s a b. a -> Cursor s b -> Cursor s a
<$ :: forall a b. a -> Cursor s b -> Cursor s a
Functor)

-- | A `TransactionIO` that also manages creation and deletion of `Cursor`s
newtype CursorTransactionIO s a = CursorTransactionIO
  ( StateT Int (ResourceT TransactionIO) a )
  deriving ((forall a b.
 (a -> b) -> CursorTransactionIO s a -> CursorTransactionIO s b)
-> (forall a b.
    a -> CursorTransactionIO s b -> CursorTransactionIO s a)
-> Functor (CursorTransactionIO s)
forall a b. a -> CursorTransactionIO s b -> CursorTransactionIO s a
forall a b.
(a -> b) -> CursorTransactionIO s a -> CursorTransactionIO s b
forall s a b.
a -> CursorTransactionIO s b -> CursorTransactionIO s a
forall s a b.
(a -> b) -> CursorTransactionIO s a -> CursorTransactionIO s b
forall (f :: * -> *).
(forall a b. (a -> b) -> f a -> f b)
-> (forall a b. a -> f b -> f a) -> Functor f
$cfmap :: forall s a b.
(a -> b) -> CursorTransactionIO s a -> CursorTransactionIO s b
fmap :: forall a b.
(a -> b) -> CursorTransactionIO s a -> CursorTransactionIO s b
$c<$ :: forall s a b.
a -> CursorTransactionIO s b -> CursorTransactionIO s a
<$ :: forall a b. a -> CursorTransactionIO s b -> CursorTransactionIO s a
Functor, Functor (CursorTransactionIO s)
Functor (CursorTransactionIO s) =>
(forall a. a -> CursorTransactionIO s a)
-> (forall a b.
    CursorTransactionIO s (a -> b)
    -> CursorTransactionIO s a -> CursorTransactionIO s b)
-> (forall a b c.
    (a -> b -> c)
    -> CursorTransactionIO s a
    -> CursorTransactionIO s b
    -> CursorTransactionIO s c)
-> (forall a b.
    CursorTransactionIO s a
    -> CursorTransactionIO s b -> CursorTransactionIO s b)
-> (forall a b.
    CursorTransactionIO s a
    -> CursorTransactionIO s b -> CursorTransactionIO s a)
-> Applicative (CursorTransactionIO s)
forall s. Functor (CursorTransactionIO s)
forall a. a -> CursorTransactionIO s a
forall s a. a -> CursorTransactionIO s a
forall a b.
CursorTransactionIO s a
-> CursorTransactionIO s b -> CursorTransactionIO s a
forall a b.
CursorTransactionIO s a
-> CursorTransactionIO s b -> CursorTransactionIO s b
forall a b.
CursorTransactionIO s (a -> b)
-> CursorTransactionIO s a -> CursorTransactionIO s b
forall s a b.
CursorTransactionIO s a
-> CursorTransactionIO s b -> CursorTransactionIO s a
forall s a b.
CursorTransactionIO s a
-> CursorTransactionIO s b -> CursorTransactionIO s b
forall s a b.
CursorTransactionIO s (a -> b)
-> CursorTransactionIO s a -> CursorTransactionIO s b
forall a b c.
(a -> b -> c)
-> CursorTransactionIO s a
-> CursorTransactionIO s b
-> CursorTransactionIO s c
forall s a b c.
(a -> b -> c)
-> CursorTransactionIO s a
-> CursorTransactionIO s b
-> CursorTransactionIO s c
forall (f :: * -> *).
Functor f =>
(forall a. a -> f a)
-> (forall a b. f (a -> b) -> f a -> f b)
-> (forall a b c. (a -> b -> c) -> f a -> f b -> f c)
-> (forall a b. f a -> f b -> f b)
-> (forall a b. f a -> f b -> f a)
-> Applicative f
$cpure :: forall s a. a -> CursorTransactionIO s a
pure :: forall a. a -> CursorTransactionIO s a
$c<*> :: forall s a b.
CursorTransactionIO s (a -> b)
-> CursorTransactionIO s a -> CursorTransactionIO s b
<*> :: forall a b.
CursorTransactionIO s (a -> b)
-> CursorTransactionIO s a -> CursorTransactionIO s b
$cliftA2 :: forall s a b c.
(a -> b -> c)
-> CursorTransactionIO s a
-> CursorTransactionIO s b
-> CursorTransactionIO s c
liftA2 :: forall a b c.
(a -> b -> c)
-> CursorTransactionIO s a
-> CursorTransactionIO s b
-> CursorTransactionIO s c
$c*> :: forall s a b.
CursorTransactionIO s a
-> CursorTransactionIO s b -> CursorTransactionIO s b
*> :: forall a b.
CursorTransactionIO s a
-> CursorTransactionIO s b -> CursorTransactionIO s b
$c<* :: forall s a b.
CursorTransactionIO s a
-> CursorTransactionIO s b -> CursorTransactionIO s a
<* :: forall a b.
CursorTransactionIO s a
-> CursorTransactionIO s b -> CursorTransactionIO s a
Applicative, Applicative (CursorTransactionIO s)
Applicative (CursorTransactionIO s) =>
(forall a b.
 CursorTransactionIO s a
 -> (a -> CursorTransactionIO s b) -> CursorTransactionIO s b)
-> (forall a b.
    CursorTransactionIO s a
    -> CursorTransactionIO s b -> CursorTransactionIO s b)
-> (forall a. a -> CursorTransactionIO s a)
-> Monad (CursorTransactionIO s)
forall s. Applicative (CursorTransactionIO s)
forall a. a -> CursorTransactionIO s a
forall s a. a -> CursorTransactionIO s a
forall a b.
CursorTransactionIO s a
-> CursorTransactionIO s b -> CursorTransactionIO s b
forall a b.
CursorTransactionIO s a
-> (a -> CursorTransactionIO s b) -> CursorTransactionIO s b
forall s a b.
CursorTransactionIO s a
-> CursorTransactionIO s b -> CursorTransactionIO s b
forall s a b.
CursorTransactionIO s a
-> (a -> CursorTransactionIO s b) -> CursorTransactionIO s b
forall (m :: * -> *).
Applicative m =>
(forall a b. m a -> (a -> m b) -> m b)
-> (forall a b. m a -> m b -> m b)
-> (forall a. a -> m a)
-> Monad m
$c>>= :: forall s a b.
CursorTransactionIO s a
-> (a -> CursorTransactionIO s b) -> CursorTransactionIO s b
>>= :: forall a b.
CursorTransactionIO s a
-> (a -> CursorTransactionIO s b) -> CursorTransactionIO s b
$c>> :: forall s a b.
CursorTransactionIO s a
-> CursorTransactionIO s b -> CursorTransactionIO s b
>> :: forall a b.
CursorTransactionIO s a
-> CursorTransactionIO s b -> CursorTransactionIO s b
$creturn :: forall s a. a -> CursorTransactionIO s a
return :: forall a. a -> CursorTransactionIO s a
Monad, Monad (CursorTransactionIO s)
Monad (CursorTransactionIO s) =>
(forall a. IO a -> CursorTransactionIO s a)
-> MonadIO (CursorTransactionIO s)
forall s. Monad (CursorTransactionIO s)
forall a. IO a -> CursorTransactionIO s a
forall s a. IO a -> CursorTransactionIO s a
forall (m :: * -> *).
Monad m =>
(forall a. IO a -> m a) -> MonadIO m
$cliftIO :: forall s a. IO a -> CursorTransactionIO s a
liftIO :: forall a. IO a -> CursorTransactionIO s a
MonadIO, MonadIO (CursorTransactionIO s)
MonadIO (CursorTransactionIO s) =>
(forall a. ResourceT IO a -> CursorTransactionIO s a)
-> MonadResource (CursorTransactionIO s)
forall s. MonadIO (CursorTransactionIO s)
forall a. ResourceT IO a -> CursorTransactionIO s a
forall s a. ResourceT IO a -> CursorTransactionIO s a
forall (m :: * -> *).
MonadIO m =>
(forall a. ResourceT IO a -> m a) -> MonadResource m
$cliftResourceT :: forall s a. ResourceT IO a -> CursorTransactionIO s a
liftResourceT :: forall a. ResourceT IO a -> CursorTransactionIO s a
MonadResource, MonadState Int)

run :: (forall s. CursorTransactionIO s a) -> TransactionIO a
run :: forall a. (forall s. CursorTransactionIO s a) -> TransactionIO a
run (CursorTransactionIO StateT Int (ResourceT TransactionIO) a
ctxio) = ResourceT TransactionIO a -> TransactionIO a
forall (m :: * -> *) a. MonadUnliftIO m => ResourceT m a -> m a
runResourceT (ResourceT TransactionIO a -> TransactionIO a)
-> (StateT Int (ResourceT TransactionIO) a
    -> ResourceT TransactionIO a)
-> StateT Int (ResourceT TransactionIO) a
-> TransactionIO a
forall b c a. (b -> c) -> (a -> b) -> a -> c
. (StateT Int (ResourceT TransactionIO) a
 -> Int -> ResourceT TransactionIO a)
-> Int
-> StateT Int (ResourceT TransactionIO) a
-> ResourceT TransactionIO a
forall a b c. (a -> b -> c) -> b -> a -> c
flip StateT Int (ResourceT TransactionIO) a
-> Int -> ResourceT TransactionIO a
forall (m :: * -> *) s a. Monad m => StateT s m a -> s -> m a
evalStateT Int
0 (StateT Int (ResourceT TransactionIO) a -> TransactionIO a)
-> StateT Int (ResourceT TransactionIO) a -> TransactionIO a
forall a b. (a -> b) -> a -> b
$ StateT Int (ResourceT TransactionIO) a
ctxio

-- | Like `Session.sql` but in a `CursorTransactionIO`. It should not attempt any statements that cannot be safely run inside a transaction.
sql :: ByteString -> CursorTransactionIO s ()
sql :: forall s. ByteString -> CursorTransactionIO s ()
sql = StateT Int (ResourceT TransactionIO) () -> CursorTransactionIO s ()
forall s a.
StateT Int (ResourceT TransactionIO) a -> CursorTransactionIO s a
CursorTransactionIO (StateT Int (ResourceT TransactionIO) ()
 -> CursorTransactionIO s ())
-> (ByteString -> StateT Int (ResourceT TransactionIO) ())
-> ByteString
-> CursorTransactionIO s ()
forall b c a. (b -> c) -> (a -> b) -> a -> c
. ResourceT TransactionIO ()
-> StateT Int (ResourceT TransactionIO) ()
forall (m :: * -> *) a. Monad m => m a -> StateT Int m a
forall (t :: (* -> *) -> * -> *) (m :: * -> *) a.
(MonadTrans t, Monad m) =>
m a -> t m a
lift (ResourceT TransactionIO ()
 -> StateT Int (ResourceT TransactionIO) ())
-> (ByteString -> ResourceT TransactionIO ())
-> ByteString
-> StateT Int (ResourceT TransactionIO) ()
forall b c a. (b -> c) -> (a -> b) -> a -> c
. TransactionIO () -> ResourceT TransactionIO ()
forall (m :: * -> *) a. Monad m => m a -> ResourceT m a
forall (t :: (* -> *) -> * -> *) (m :: * -> *) a.
(MonadTrans t, Monad m) =>
m a -> t m a
lift (TransactionIO () -> ResourceT TransactionIO ())
-> (ByteString -> TransactionIO ())
-> ByteString
-> ResourceT TransactionIO ()
forall b c a. (b -> c) -> (a -> b) -> a -> c
. ByteString -> TransactionIO ()
TransactionIO.sql

-- | Like `Session.statement` but in a `CursorTransactionIO`. It should not any statements that cannot be safely run inside a transaction.
statement :: params -> Statement params result -> CursorTransactionIO s result
statement :: forall params result s.
params -> Statement params result -> CursorTransactionIO s result
statement params
params Statement params result
stmt = StateT Int (ResourceT TransactionIO) result
-> CursorTransactionIO s result
forall s a.
StateT Int (ResourceT TransactionIO) a -> CursorTransactionIO s a
CursorTransactionIO (StateT Int (ResourceT TransactionIO) result
 -> CursorTransactionIO s result)
-> (TransactionIO result
    -> StateT Int (ResourceT TransactionIO) result)
-> TransactionIO result
-> CursorTransactionIO s result
forall b c a. (b -> c) -> (a -> b) -> a -> c
. ResourceT TransactionIO result
-> StateT Int (ResourceT TransactionIO) result
forall (m :: * -> *) a. Monad m => m a -> StateT Int m a
forall (t :: (* -> *) -> * -> *) (m :: * -> *) a.
(MonadTrans t, Monad m) =>
m a -> t m a
lift (ResourceT TransactionIO result
 -> StateT Int (ResourceT TransactionIO) result)
-> (TransactionIO result -> ResourceT TransactionIO result)
-> TransactionIO result
-> StateT Int (ResourceT TransactionIO) result
forall b c a. (b -> c) -> (a -> b) -> a -> c
. TransactionIO result -> ResourceT TransactionIO result
forall (m :: * -> *) a. Monad m => m a -> ResourceT m a
forall (t :: (* -> *) -> * -> *) (m :: * -> *) a.
(MonadTrans t, Monad m) =>
m a -> t m a
lift (TransactionIO result -> CursorTransactionIO s result)
-> TransactionIO result -> CursorTransactionIO s result
forall a b. (a -> b) -> a -> b
$ params -> Statement params result -> TransactionIO result
forall params result.
params -> Statement params result -> TransactionIO result
TransactionIO.statement params
params Statement params result
stmt

ignoreFailedTransactionError :: MonadError QueryError m => m () -> m ()
ignoreFailedTransactionError :: forall (m :: * -> *). MonadError QueryError m => m () -> m ()
ignoreFailedTransactionError m ()
sess =
  m () -> (QueryError -> m ()) -> m ()
forall a. m a -> (QueryError -> m a) -> m a
forall e (m :: * -> *) a.
MonadError e m =>
m a -> (e -> m a) -> m a
catchError m ()
sess ((QueryError -> m ()) -> m ()) -> (QueryError -> m ()) -> m ()
forall a b. (a -> b) -> a -> b
$ \QueryError
qe -> case QueryError
qe of
    QueryError ByteString
_ [Text]
_ (ResultError (ServerError ByteString
"25P02" ByteString
_ Maybe ByteString
_ Maybe ByteString
_ Maybe Int
_)) -> () -> m ()
forall a. a -> m a
forall (f :: * -> *) a. Applicative f => a -> f a
pure ()
    QueryError
_ -> QueryError -> m ()
forall a. QueryError -> m a
forall e (m :: * -> *) a. MonadError e m => e -> m a
throwError QueryError
qe

-- | Run a `Statement` using a cursor
declareCursorFor :: params -> Statement params result -> CursorTransactionIO s (Cursor s result)
declareCursorFor :: forall params result s.
params
-> Statement params result
-> CursorTransactionIO s (Cursor s result)
declareCursorFor params
params Statement params result
stmt = do
  UnliftIO forall a. TransactionIO a -> IO a
runInIO <- StateT Int (ResourceT TransactionIO) (UnliftIO TransactionIO)
-> CursorTransactionIO s (UnliftIO TransactionIO)
forall s a.
StateT Int (ResourceT TransactionIO) a -> CursorTransactionIO s a
CursorTransactionIO (StateT Int (ResourceT TransactionIO) (UnliftIO TransactionIO)
 -> CursorTransactionIO s (UnliftIO TransactionIO))
-> (TransactionIO (UnliftIO TransactionIO)
    -> StateT Int (ResourceT TransactionIO) (UnliftIO TransactionIO))
-> TransactionIO (UnliftIO TransactionIO)
-> CursorTransactionIO s (UnliftIO TransactionIO)
forall b c a. (b -> c) -> (a -> b) -> a -> c
. ResourceT TransactionIO (UnliftIO TransactionIO)
-> StateT Int (ResourceT TransactionIO) (UnliftIO TransactionIO)
forall (m :: * -> *) a. Monad m => m a -> StateT Int m a
forall (t :: (* -> *) -> * -> *) (m :: * -> *) a.
(MonadTrans t, Monad m) =>
m a -> t m a
lift (ResourceT TransactionIO (UnliftIO TransactionIO)
 -> StateT Int (ResourceT TransactionIO) (UnliftIO TransactionIO))
-> (TransactionIO (UnliftIO TransactionIO)
    -> ResourceT TransactionIO (UnliftIO TransactionIO))
-> TransactionIO (UnliftIO TransactionIO)
-> StateT Int (ResourceT TransactionIO) (UnliftIO TransactionIO)
forall b c a. (b -> c) -> (a -> b) -> a -> c
. TransactionIO (UnliftIO TransactionIO)
-> ResourceT TransactionIO (UnliftIO TransactionIO)
forall (m :: * -> *) a. Monad m => m a -> ResourceT m a
forall (t :: (* -> *) -> * -> *) (m :: * -> *) a.
(MonadTrans t, Monad m) =>
m a -> t m a
lift (TransactionIO (UnliftIO TransactionIO)
 -> CursorTransactionIO s (UnliftIO TransactionIO))
-> TransactionIO (UnliftIO TransactionIO)
-> CursorTransactionIO s (UnliftIO TransactionIO)
forall a b. (a -> b) -> a -> b
$ TransactionIO (UnliftIO TransactionIO)
forall (m :: * -> *). MonadUnliftIO m => m (UnliftIO m)
askUnliftIO
  Int
cursorIx <- CursorTransactionIO s Int
forall s (m :: * -> *). MonadState s m => m s
get
  let cursorVar :: ByteString
cursorVar = Builder -> ByteString
toByteString (Builder -> ByteString) -> Builder -> ByteString
forall a b. (a -> b) -> a -> b
$ Builder
"Hasql_CursorTransactionIO_" Builder -> Builder -> Builder
forall a. Semigroup a => a -> a -> a
<> Int -> Builder
forall a. Integral a => a -> Builder
asciiIntegral Int
cursorIx
  (Int -> Int) -> CursorTransactionIO s ()
forall s (m :: * -> *). MonadState s m => (s -> s) -> m ()
modify' (Int -> Int -> Int
forall a. Num a => a -> a -> a
+Int
1)
  (ReleaseKey
_, Cursor s result
cursor) <- IO (Cursor s result)
-> (Cursor s result -> IO ())
-> CursorTransactionIO s (ReleaseKey, Cursor s result)
forall (m :: * -> *) a.
MonadResource m =>
IO a -> (a -> IO ()) -> m (ReleaseKey, a)
allocate
    (TransactionIO (Cursor s result) -> IO (Cursor s result)
forall a. TransactionIO a -> IO a
runInIO (TransactionIO (Cursor s result) -> IO (Cursor s result))
-> TransactionIO (Cursor s result) -> IO (Cursor s result)
forall a b. (a -> b) -> a -> b
$ ByteString
-> params
-> Statement params result
-> TransactionIO (Cursor s result)
forall params result s.
ByteString
-> params
-> Statement params result
-> TransactionIO (Cursor s result)
newCursor ByteString
cursorVar params
params Statement params result
stmt)
    (TransactionIO () -> IO ()
forall a. TransactionIO a -> IO a
runInIO (TransactionIO () -> IO ())
-> (Cursor s result -> TransactionIO ())
-> Cursor s result
-> IO ()
forall b c a. (b -> c) -> (a -> b) -> a -> c
. TransactionIO () -> TransactionIO ()
forall (m :: * -> *). MonadError QueryError m => m () -> m ()
ignoreFailedTransactionError (TransactionIO () -> TransactionIO ())
-> (Cursor s result -> TransactionIO ())
-> Cursor s result
-> TransactionIO ()
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Cursor s result -> TransactionIO ()
forall s a. Cursor s a -> TransactionIO ()
closeCursor)
  Cursor s result -> CursorTransactionIO s (Cursor s result)
forall a. a -> CursorTransactionIO s a
forall (f :: * -> *) a. Applicative f => a -> f a
pure Cursor s result
cursor

newCursor :: ByteString -> params -> Statement params result -> TransactionIO (Cursor s result)
newCursor :: forall params result s.
ByteString
-> params
-> Statement params result
-> TransactionIO (Cursor s result)
newCursor ByteString
cursorVar params
params (Statement ByteString
query Params params
encoder Result result
decoder Bool
prepare) = do
  let cursorQuery :: ByteString
cursorQuery = 
        ByteString
"DECLARE " ByteString -> ByteString -> ByteString
forall a. Semigroup a => a -> a -> a
<> ByteString
cursorVar ByteString -> ByteString -> ByteString
forall a. Semigroup a => a -> a -> a
<> ByteString
" NO SCROLL CURSOR FOR " ByteString -> ByteString -> ByteString
forall a. Semigroup a => a -> a -> a
<> ByteString
query
  params -> Statement params () -> TransactionIO ()
forall params result.
params -> Statement params result -> TransactionIO result
TransactionIO.statement params
params (ByteString
-> Params params -> Result () -> Bool -> Statement params ()
forall a b.
ByteString -> Params a -> Result b -> Bool -> Statement a b
Statement ByteString
cursorQuery Params params
encoder Result ()
noResult Bool
prepare)
  Cursor s result -> TransactionIO (Cursor s result)
forall a. a -> TransactionIO a
forall (f :: * -> *) a. Applicative f => a -> f a
pure (Cursor s result -> TransactionIO (Cursor s result))
-> Cursor s result -> TransactionIO (Cursor s result)
forall a b. (a -> b) -> a -> b
$ ByteString -> Result result -> Cursor s result
forall s a. ByteString -> Result a -> Cursor s a
Cursor ByteString
cursorVar Result result
decoder

closeCursor :: Cursor s a -> TransactionIO ()
closeCursor :: forall s a. Cursor s a -> TransactionIO ()
closeCursor (Cursor ByteString
cursorVar Result a
_) = do
  let closeQuery :: ByteString
closeQuery = ByteString
"CLOSE " ByteString -> ByteString -> ByteString
forall a. Semigroup a => a -> a -> a
<> ByteString
cursorVar
  () -> Statement () () -> TransactionIO ()
forall params result.
params -> Statement params result -> TransactionIO result
TransactionIO.statement () (ByteString -> Params () -> Result () -> Bool -> Statement () ()
forall a b.
ByteString -> Params a -> Result b -> Bool -> Statement a b
Statement ByteString
closeQuery Params ()
noParams Result ()
noResult Bool
True)

-- | Fetch results from a cursor
fetchWithCursor :: Cursor s a -> CursorTransactionIO s a
fetchWithCursor :: forall s a. Cursor s a -> CursorTransactionIO s a
fetchWithCursor (Cursor ByteString
cursorVar Result a
decoder) = do
  let fetchQuery :: ByteString
fetchQuery = ByteString
"FETCH " ByteString -> ByteString -> ByteString
forall a. Semigroup a => a -> a -> a
<> ByteString
cursorVar
  () -> Statement () a -> CursorTransactionIO s a
forall params result s.
params -> Statement params result -> CursorTransactionIO s result
statement () (ByteString -> Params () -> Result a -> Bool -> Statement () a
forall a b.
ByteString -> Params a -> Result b -> Bool -> Statement a b
Statement ByteString
fetchQuery Params ()
noParams Result a
decoder Bool
True)