TVars

Shared memory locations that support atomic memory transactions.

Create a new TVar holding a value supplied

Return the current value stored in a TVar

Write the supplied value into a TVar

IO version of newTVar. This is useful for creating top-level TVars using unsafePerformIO, because using atomically inside unsafePerformIO isn't possible.

Return the current value stored in a TVar. This is equivalent to

  readTVarIO = atomically . readTVar

but works much faster, because it doesn't perform a complete transaction, it just reads the current value of the TVar.

Set the value of returned TVar to True after a given number of microseconds. The caveats associated with threadDelay also apply.