> (base) mattei@mbp-touch-bar Scheme-PLUS-for-Guile % guile > GNU Guile 3.0.8.99-f3ea8 > Copyright (C) 1995-2022 Free Software Foundation, Inc. > > Guile comes with ABSOLUTELY NO WARRANTY; for details type `,show w'. > This program is free software, and you are welcome to redistribute it > under certain conditions; type `,show c' for details. > > Enter `,help' for help. > scheme@(guile-user)> (define-syntax test-it > (lambda (stx) > (syntax-case stx () > ((_ term1) > (with-syntax ((var (syntax->datum #'term1))) > #'var))))) > scheme@(guile-user)> (test-it (+ 2 3)) > While compiling expression: > Syntax error: > unknown file:#f:#f: encountered raw symbol in macro output in subform + of > (test-it (+ 2 3))
As the error message says, your macro contains the raw symbol `term1`. The expression (syntax->datum #'term1) is equivalent to 'term1 . What's raising the error is not with-syntax itself, it's the fact that a hygienic macro must return syntax objects, and a raw symbol is not a syntax object. Kawa and Racket probably have some fallback where the macro becomes non-hygienic when it returns raw symbols. But R6RS makes it clear that this is not standard Scheme. See https://www.r6rs.org/final/html/r6rs-lib/r6rs-lib-Z-H-13.html#node_sec_12.2 """ a syntax object is: - a pair of syntax objects, - a vector of syntax objects, - a nonpair, nonvector, nonsymbol value, or - a wrapped syntax object """ """ A transformation procedure is a procedure that must accept one argument, a wrapped syntax object (section 12.2) representing the input, and return a syntax object (section 12.2) representing the output. """
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