The trend to put meaningless but catchy adjectives, like "safe" and "predictable", as if everything else is opposite, is misleading.
Designers of classic languages were not some arrogant punks (they were brilliant, like David Moon and other guys of his generation), and the most of findamental problems were well understood in times of Standard ML or Common Lisp.
So, in comparison to C or C++ it might be "predictable" and even more "safe", but in comparison with well-researched classic languages, these mere redundant adjectives.