Polysemy.Resource

Effect

data Resource m a where

An effect capable of providing bracket semantic. Interpreters for this will successfully run the deallocation action even in the presence of other short-circuiting effects.

Constructors

Bracket

Fields

• :: m a

  Action to allocate a resource.

• -> (a -> m ())

  Action to cleanup the resource. This is guaranteed to be called.

• -> (a -> m b)

  Action which uses the resource.

• -> Resource m b

Instances

type DefiningModule Resource

Defined in Polysemy.Resource

type DefiningModule Resource = "Polysemy.Resource"

Actions

bracket :: forall a b. forall r. Member Resource r => Semantic r a -> (a -> Semantic r ()) -> (a -> Semantic r b) -> Semantic r b

Interpretations

runResource

Arguments

:: Member (Lift IO) r

=> (forall x. Semantic r x -> IO x)

Strategy for lowering a Semantic action down to IO. This is likely some combination of runM and other interpters composed via .@.

-> Semantic (Resource ': r) a

-> Semantic r a

Run a Resource effect via in terms of bracket.