I agree that prison isn’t meant to be fun.  But an enlightened society knows that prison is for two main reasons:

1.	 To protect society from dangerous people.
2.	To try to rehabilitate those people so that they can become contributing members of society.

The punishment aspect simply doesn’t work.  One only has to look to the United States record – violent and dangerous prisons, lengthy sentences, and the highest rates of incarceration and recidivism in the Western world.

Segregation should be a tool of last resort, used only when no other method is available to protect prison staff and/other inmates.  The evidence of the harm caused by prolonged isolation is overwhelming; anyone who has been through it is very unlikely to ever be fully rehabilitated.