af26503 · squeal · git.iko.soy

MonadBaseControl instance for PoolPQ

af26503Eitan Chatav9 years ago

squeal-postgresql/src/Squeal/PostgreSQL/Pool.hs+17

@@ -3,7 +3,9 @@

3 , FlexibleContexts

4 , FlexibleInstances

5 , MultiParamTypeClasses

6+ , RankNTypes

6 , ScopedTypeVariables

7 , ScopedTypeVariables

8+ , TypeFamilies

7 , UndecidableInstances

9 , UndecidableInstances

8#-}

10#-}

@@ -59,3 +61,18 @@ instance MonadBaseControl IO io => MonadPQ schema (PoolPQ schema io) where

59 (result, _ :: Connection schema) <- flip runPQ conn $

61 (result, _ :: Connection schema) <- flip runPQ conn $

60 liftPQ m

62 liftPQ m

61 return result

63 return result

64+

65+-- | A snapshot of the state of a `PoolPQ` computation.

66+type PoolPQRun schema =

67+ forall m x. Monad m => PoolPQ schema m x -> m x

68+

69+-- | Helper function in defining `MonadBaseControl` instance for `PoolPQ`.

70+poolpqliftWith :: Functor m => (PoolPQRun schema -> m a) -> PoolPQ schema m a

71+poolpqliftWith f = PoolPQ $ \ pool ->

72+ (f $ \ pq -> runPoolPQ pq pool)

73+

74+instance MonadBaseControl b m => MonadBaseControl b (PoolPQ schema m) where

75+ type StM (PoolPQ schema m) x = StM m x

76+ liftBaseWith f =

77+ poolpqliftWith $ \ run -> liftBaseWith $ \ runInBase -> f $ runInBase . run

78+ restoreM = PoolPQ . const . restoreM