Using expr/c to attach a contract to a macro sub-pattern doesn't seem to work with ~optional, even when the attribute is bound with #:defaults.
For example, this program: > #lang racket (require (for-syntax syntax/parse)) > (define-syntax (example stx) > (syntax-parse stx > [(_ (~optional (~seq #:return val) > #:defaults ([val #'42]))) > #:declare val (expr/c #'(or/c list? #f)) > #'val.c])) > (example) reports the following error: > val.c: bad attribute value for syntax template > attribute value: #f > expected for attribute: syntax > sub-value: #f > expected for sub-value: syntax in: val.c Is there a better way to do this? -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
