Don't public libraries have two separate sections? One for youths, and
one for adults? The libraries that I've been two do that, and there is
usually a lobby between the two. Make it a rule, that they can go
there, only to stay in the adult section. That is, if they were
released on parole. If they had to serve their entire sentence without
parole, then they should be banned. (If you're a little more liberal
than that, then they need to have another adult with them to supervise
until they are sure that the person can go to the library without a
worry that they'll repeat their offense. Libraries are usually secure,
anyway.
Sending criminals to prison is supposed to punish them, and once they
prove that they've learned their lesson and can re-enter society, then
they should be given a chance. They let armed robbers out of prison
who have turned out fine, and frauds as well. For pedophiles, since
this is a more serious issue:
They should be supervised for quite some time, and be occasionally left on their own (not knowing that there will be video surveillance or some sort of monitoring like that), and as soon as they show the first sign that they might repeat the offense, they'll be thrown back in jail before they can hurt anyone. If they knowingly step within
the five hundred yards without a supervisor, their supervisor (or
someone else who's spying on them) will arrest him.
You have to test them, because some of them might actually turn out
fine after prison. (The several thousand times they got the tar
badly kicked out of them in jail, would have taught them that lesson).