The following program run with "plt-r6rs":
#!r6rs
(import (rnrs))
(guard (E (else
(write (condition-message E))(newline)
(write (syntax-violation-form E))(newline)
(write (syntax-violation-subform E))(newline)
#t))
(syntax-violation 'doit "the message" #'(display) #'display))
prints:
"the message"
#<syntax:/home/marco/var/tmp/proof.sps:11:42 (display)>
#<syntax:/home/marco/var/tmp/proof.sps:11:54 display>
which is good; but the following program:
#!r6rs
(import (rnrs)
(rnrs eval))
(guard (E (else
(write (condition-message E))(newline)
(write (syntax-violation-form E))(newline)
(write (syntax-violation-subform E))(newline)
#t))
(eval '(let ()
(define-syntax doit
(lambda (stx)
(syntax-case stx ()
((?id)
(syntax-violation 'doit "the message" stx (syntax->datum
#'?id))))))
(doit))
(environment '(rnrs))))
prints:
"doit: the message at: doit in: (doit)"
#<syntax doit>
#f
that is: the message is changed, the form field is
overwritten with the subform field, the subform field is set
to #f, the (sub)form field is converted to a syntax object
(it was a sexpr when given to SYNTAX-VIOLATION).
This is annoying for me, because I rely on the fields in
my test suite to validate reaction to syntax errors. Can
the correct behaviour be enforced in the implementation of
EVAL?
TIA
--
Marco Maggi
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