On Sunday 07 November 2004 16:18, you wrote:

Adrian Hey wrote:

...

I'm not at all convinced, having not seen or groked either the "before" or "after" code. Perhaps you could show how this would work with an even simpler example, the one that I posted concerning the use of oneShot to create a top level (I.E. exportable) userInit.

AFAICS the only alternative to..

userInit <- oneShot realInit

is to export realInit, have users create their own userInit, and then pass that around as an argument to everything that might make use of userInit.

The way I would do it would be to have an init function that initialises an abstract data structure. Because the results of the init function are stateless and not in a global variable it does not matter if the user calls it twice.

Yes, whenever possible I would use this approach. Unfortunately, there are libraries (or just modules) that need to do some IO action in order to produce the (A)DT. In this case it _will_ make a difference how often you call it. But then this is just how IO actions are by nature, isn't it? Ben