[asgard1024]

I am aware of lifting, but the question is if you have monadic code and pure code in different modules (or you need to go through function which was previously pure), where do you put the lift? If you put it outside the module, you break the modularity. If you put it inside, well then you might as well make the functions monadic in the first place. Basically if you have functions in module API (which may be in itself pure) that may eventually end up calling unpure functions, you have to provision for that somehow, either in the module by making them monadic, or in the caller via lifting. Either way, it's not as clean as it could be.

But I thought about it some more, and to me it seems that actually parametrizing the functions to outside world is not that bad; it's a kind of dependency injection, and seems fine. What is really problematic is returning all the IOs (or other monads) from them; especially since you cannot curry return parameters just like you can entry parameters. So even if that could be replaced by some other mechanism, it would be helpful.

But I didn't know unsafePerformIO, sounds like it can be helpful in some cases.