[Haskell-cafe] Correspondence between libraries and modules

Hi there, I've only dabbled in Haskell, so please excuse my ignorance: why isn't there a 1-to-1 mapping between libraries and modules? As I understand it, a library can provide any number of unrelated modules, and conversely, a single module could be provided by more than one library. I can see how this affords library authors more flexibility, but at a cost: there is no longer a single, unified view of the library universe. (The alternative would be for every module to be its own, hermetic library.) So I'm very interested in the rationale behind that aspect of the library system. Thanks! Alvaro