Delay a until at least the specified amount of time has passed.

Delay until a specific UTCTime has occured (at least once). This is slighly confusing, as we can't guarantee we don't return only after the second occurence of the UTCTime under certain leap second handling regimes. Consider for example when delayTill is called during a leap second occurence, where the system clock jumps back and repeats the second. As there is no indication the time has already passed once, we must wait until the second occurence.

Run an monad action for at least a specific number of seconds, but not much more.

Run a monadic action until it produces a result or a specific time occures. Leap second handling as per delayTill.

We hold the CallbackHandle in an MVar so we don't race on update/cancelation and executing the callback. Updating or canceling holds the lock, which is also required to export the action.

Run a callback after a period of time has passed.

Run a callback at a specific time.

Change an existing, unexecuted or canceled callbak to run after a specific period of time from the call of updateCallbackToAfter.

Change an existing, unexecuted or canceled callbak to run after at a specific time.

Terminate an unexecuted callback.

Calculate the number of microseconds of delay a value represents. Instances must round up for correctness.