|Portability||non-portable (requires concurrency)|
FFI datatypes and operations that use or require concurrency (GHC only).
These functions generalize their namesakes in the portable
Foreign.ForeignPtr module by allowing arbitrary
as finalizers. These finalizers necessarily run in a separate
thread, cf. Destructors, Finalizers and Synchronization,
by Hans Boehm, POPL, 2003.
Turns a plain memory reference into a foreign object by associating a finalizer - given by the monadic operation - with the reference. The finalizer will be executed after the last reference to the foreign object is dropped. There is no guarantee of promptness, and in fact there is no guarantee that the finalizer will eventually run at all.