Are you trying to insert a literal '@'? You need to escape it as '@@'. I believe racket has some support for variable interpolation that is triggered by '@', and the 'eof' error is because it's trying to read a variable name after the @, but there's nothing but a space.
For the record, this doesn't have anything to do with Racket. This is atstrings, a feature of Arc.
Atstrings is off by default in plain Arc 3.1, but it's activated by the line (declare 'atstrings t), and news.arc includes that line for its own purposes.
