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Showing content from http://docs.racket-lang.org/reference/stxparam.html below:

12.5 Syntax Parameters

12.5 Syntax Parameters🔗ℹ

The id can be used with syntax-parameterize or syntax-parameter-value (in a transformer). If expr produces a procedure of one argument or a make-set!-transformer result, then id can be used as a macro. If expr produces a make-rename-transformer result, then id can be used as a macro that expands to a use of the target identifier, but syntax-local-value of id does not produce the target’s value.

Examples:

Each id must be bound to a syntax parameter using define-syntax-parameter. Each expr is an expression in the transformer environment. During the expansion of the body-exprs, the value of each expr is bound to the corresponding id.

If an expr produces a procedure of one argument or a make-set!-transformer result, then its id can be used as a macro during the expansion of the body-exprs. If expr produces a make-rename-transformer result, then id can be used as a macro that expands to a use of the target identifier, but syntax-local-value of id does not produce the target’s value.

Examples:

Examples:

Added in version 6.3.0.14 of package base.

12.5.1 Syntax Parameter Inspection🔗ℹ

This binding is provided for-syntax by racket/stxparam, since it is normally used in a transformer. It is provided normally by racket/stxparam-exptime.

Using make-parameter-rename-transformer is analogous to defining a procedure that calls a parameter. Such a procedure can be exported to others to allow access to the parameter value, but not to change the parameter value. Similarly, make-parameter-rename-transformer allows a syntax parameter to be used as a macro, but not changed.

The result of make-parameter-rename-transformer is not treated specially by syntax-local-value, unlike the result of make-rename-transformer.

This binding is provided for-syntax by racket/stxparam, since it is normally used in a transformer. It is provided normally by racket/stxparam-exptime.


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