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struct/ ctc

6.7 Extending the Syntax of Signatures

(define-signature-form sig-form-id expr)
(define-signature-form (sig-form-id id) body ...+)
Binds sig-form-id for use within a define-signature form.

In the first form, the result of expr must be a transformer procedure. In the second form, sig-form-id is bound to a transformer procedure whose argument is id and whose body is the bodys. The result of the transformer must be a list of syntax objects, which are substituted for a use of sig-form-id in a define-signature expansion. (The result is a list so that the transformer can produce multiple declarations; define-signature has no splicing begin form.)

(struct/ctc id ([field contract-expr] ...) struct-option ...)
field = id
  | [id #:mutable]
struct-option = #:mutable
  | #:omit-constructor
  | #:omit-define-syntaxes
  | #:omit-define-values
For use with define-signature. The struct/ctc form works similarly to struct, but the constructor, predicate, field accessors, and field mutators are contracted appropriately.