CODEWITHSUNDEEP
racket
thor
thor

Reputation: 22460

What is a good replacement for r6rs syntax-violation in racket?

According to DrRacket Docs, the syntax-violation form is defined in rnrs/syntax-case-6. But I'd like to use the syntax-case from racket/base and avoid importing rnrs/syntax-case-6 (and r6rs in general since it seems to have a different syntax-case implementation than the racket/base).

Is there another function from racket/base or racket/racket that can replace syntax-violation? Or, should I write my own version that raises an exception?

--Edit--

I tried to import syntax-violation from racket/base, but it seems to be missing from there:

racket 
Welcome to Racket v8.6 [cs].
> syntax-violation
syntax-violation: undefined;
 cannot reference an identifier before its definition                             
  in module: top-level                                                            
 [,bt for context]                                                                
> (require racket/base)
> syntax-violation
syntax-violation: undefined;
 cannot reference an identifier before its definition                             
  in module: top-level                                                            
 [,bt for context]                                                                
> (syntax-violation #f "error message" #f)
syntax-violation: undefined;
 cannot reference an identifier before its definition                             
  in module: top-level                                                            
 [,bt for context]

Upvotes: 0

Views: 49

Answers (2)

Shawn
Shawn

Reputation: 52334

I use raise-syntax-error in macro error handling, which raises an exception of type exn:fail:syntax. From the docs:

Macros use this procedure to report syntax errors.

Example:

(define-syntax (example stx)
  (syntax-case stx ()
    ((_) (raise-syntax-error 'example "no arguments" stx))
    ((_ x) #'(do-something-with x))))

Upvotes: 1

Sorawee Porncharoenwase
Sorawee Porncharoenwase

Reputation: 6502

You can use raise-syntax-error directly.

Internally, syntax-violation is implemented in Racket by using raise-syntax-error.

Upvotes: 1

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