Have you ever wanted to restrict an IO action such that it could only be invoked once? Now you can with System.IO.Memoize.once (formerly known as ioMemo).
(Moving to cafe for dicussion ...)
I may want a one-time only IO action, although so far the need hasn't arisen yet. ;)
In the spirit of pilfering while the buns are still hot out of the oven, is there a backstory for this package you could possibly sketch out? Some canonical use case maybe?