actually inquirer is right about most of those communist states not actual being communist states. one of the strategys of marxism was vanguardism, where basically an organization (ie a temparary oligarchy) would lead the communist state in the very early stages and then reliquinsh control to the people when communism could be established (ie revolution complete). the bolshevik party is an example
the problem with this was that when you give people power, they rarely give it back. i cant think of a single communist state that moved past the vanguard stage. most descended into oligarchy (china is a good example), or dictatorship.
as for the thingo about "santa claus" sentances, the move towards recognizing mitigating circumstances has more to do with current criminological theory. eg strain theory, social disorganization theory..
the move away from punitive legal structures is in my opinion a sort of social maturity. rather than hit the kid, work out why the kid fucked up, and try to prevent it from happening again
the whole eye for an eye shtick is medieval