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define-signature-form
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7.7 Extending the Syntax of Signatures🔗ℹ

syntax

(define-signature-form sig-form-id expr)

(define-signature-form (sig-form-id id) body ...+)
(define-signature-form (sig-form-id id intro-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 that accepts one argument. In the second form, sig-form-id is bound to a transformer procedure whose argument is id and whose body is the bodys. The third form is like the second one, but intro-id is bound to a procedure that is analogous to syntax-local-introduce for the signature-form expansion.

The result of the transformer procedure 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.)

Changed in version 8.1.0.7 of package base: Added support for the form with a transformer expr.

syntax

(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.

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