+ ( Allocate stack space first using rsp!,
+ then copy objects from list. )
+
+ car drop
+ rsp0 + rsp!
+
+ R> R> 2dup cdr
+ 2swap
+ car drop 0 swap do
+ 2dup car drop
+ rsp0 i + 1 + !
+ cdr
+ 1- +loop
+
+ 2drop
+ trace
+ >R \ restore original top of return stack