is same thing as(unless (= 0 1)(print "55")(print "66"))
However, in CL and Scheme, unless is "pessimistic when."(if (not (= 0 1))(print "55")(print "66"))
So, original expression prints 5566 in CL and Scheme and 55 in Newlisp.(when (not (= 0 1))(print "55")(print "66"))
It might be good to synchronize that with CL and Scheme, because difference can be source of the bugs and reason for complains, and because CL and Scheme semantics seems to be more beneficial - it spares one (begin) - while Newlisp version only change the order of the alternative s-expression.
Maybe some other keyword could be used for "unless" in the current meaning, if someone think it is useful.