Does prison work?

A question much in the news at present, and of course it all depends on what you mean by "work". Prison works to the extent that while they're banged up, prisoners cannot commit other offences. But if it then simply turns them out better equipped for and more motivated towards a life of crime, then it clearly doesn't. Not for nothing are prisons referred to as "universities of crime". Re-offending rates are horribly high. So it depends on what you are looking for really. doesn't it? I've had my say on this before - in my opinion, prison should be used only where a person presents a positive danger to society, or some member(s) thereof. Otherwise the emphasis should be on restitution and rehabilitation.