- (opt-number MSG [RO [PRED]])syntax
opt-body element for number values.
- MSG
- (or string (string *)) ; message, * is default value
- RO
- (or (required KIND) (optional KIND) KIND) ; requirement
- PRED
- (string -> boolean) ; predicate
((size s) ,@(opt-number ("sample size" *sample-size*) (required INTEGER) (conjoin integer? positive?)))