I should add that in trying to write code that sucks less, this implementation is minimally POSIX compliant. That is, strict POSIX compliance with no extensions. As such operators cannot be used as strings, which is acceptable and explicitly mentioned in the POSIX specification for expr[0].
[0]http://pubs.opengroup.org/onlinepubs/9699919799/utilities/expr.html#tag_20_42_16 emg
