Cauldron.Managed

The Managed monad for handling resources

data Managed a

This is a copy of the Managed type from the managed package, with a dodgy MonadFix instance tacked on.

Instances

MonadIO Managed

Defined in Cauldron.Managed

Methods

liftIO :: IO a -> Managed a

MonadWiring Managed

Defined in Cauldron.Builder

Associated Types

type ArgsApplicative Managed

Defined in Cauldron.Builder

type ArgsApplicative Managed = Identity

type ConstructorMonad Managed

Defined in Cauldron.Builder

type ConstructorMonad Managed = Managed

Methods

_val_ :: (Typeable bean, HasCallStack) => ArgsApplicative Managed bean -> Managed (ArgsApplicative Managed bean)

_eff_ :: (Typeable bean, HasCallStack) => ArgsApplicative Managed (ConstructorMonad Managed bean) -> Managed (ArgsApplicative Managed bean)

Applicative Managed

Defined in Cauldron.Managed

Methods

pure :: a -> Managed a

(<*>) :: Managed (a -> b) -> Managed a -> Managed b

liftA2 :: (a -> b -> c) -> Managed a -> Managed b -> Managed c

(*>) :: Managed a -> Managed b -> Managed b

(<*) :: Managed a -> Managed b -> Managed a

Functor Managed

Defined in Cauldron.Managed

Methods

fmap :: (a -> b) -> Managed a -> Managed b

(<$) :: a -> Managed b -> Managed a

Monad Managed

Defined in Cauldron.Managed

Methods

(>>=) :: Managed a -> (a -> Managed b) -> Managed b

(>>) :: Managed a -> Managed b -> Managed b

return :: a -> Managed a

MonadFix Managed

This instance is a little dodgy (continuation-like monads don't have proper MonadFix instances) but it is nevertheless useful because it lets us use Managed with allowSelfDeps. Follow the recommendations for the managed function.

"if you embrace the unsafety, it could be a fun way to tie knots."

Defined in Cauldron.Managed

Methods

mfix :: (a -> Managed a) -> Managed a

type ArgsApplicative Managed

Defined in Cauldron.Builder

type ArgsApplicative Managed = Identity

type ConstructorMonad Managed

Defined in Cauldron.Builder

type ConstructorMonad Managed = Managed

managed :: (forall r. (a -> IO r) -> IO r) -> Managed a

Build a Managed value from a withFoo-style resource-handling function that accepts a continuation, like withFile.

Passing functions that do weird things like running their continuation twice will tear apart the fabric of reality. Why would you want to do that? Pass only withFoo-style functions.

with :: Managed a -> (a -> IO b) -> IO b

Make use of the managed resource by supplying a callback.