System.IOR.Resource

Resource management in the IOR monad.

Documentation

data Resource r a

Resource r a wraps a resource of type a so it can be managed inside region r and automatically released upon exit from r.

Instances

Typeable2 Resource

Eq (Resource r a)

(Data r, Data a) => Data (Resource r a)

getResource :: Resource r a -> a

Extract a from the Resource wrapper.

manage :: a -> (a -> IO ()) -> IOR r rs (Resource r a)

manage a f will create a new Resource wrapper around the value of type a in region r, given a finalizer f. Each finalizer is guaranteed to automatically be called upon exit from the region. Finalizers are called in the last in, first out fashion. So the finalizer of the very last resource allocated will be the first to get called.

Note that finalizers must not throw any errors. Failing to ensure that all errors in a finalizer are handled may result in a resource leak.

release :: RElem r' rs => Resource r' a -> IOR r rs ()

release res is used to force the resource res to be released immediately. Finalizer for res will be called and removed from the stack of finalizers in region r'.