On 12/16/2009 04:37 PM, Sam TH wrote:
On Wed, Dec 16, 2009 at 6:05 PM, Carl Eastlund<carl.eastl...@gmail.com> wrote:
On Wed, Dec 16, 2009 at 5:19 PM, Sam TH<sa...@ccs.neu.edu> wrote:
The program at the end of this message behaves in arbitrary ways. In
particular, it segfaults on my system. However, this should be safe:
Typed Scheme is checking that only vectors are passed to `f'. But the
`cheater' macro uses `local-expand' to extract a reference to `f', and
use it in arbitrary ways.
You provided 'f'. Certificates do not protect identifiers that are
provided from the module that defines them.
As Jay points out, I didn't really provide `f'. I provided a
rename-transformer that points to `f'. Here's a more explicit version
of the original module:
(module m typed/scheme
(require scheme/unsafe/ops (for-syntax scheme/base))
(: f ((Vectorof (U)) -> Any))
(define (f x) (unsafe-vector-length x))
(define-syntax f*
(make-rename-transformer #'f))
(provide (rename-out [f* f])))
This suggests to me that this is a bug in the interaction of
rename-transformers and certificates.
I don't have an answer, but it seems to me that since you are providing
*something* that the thing you provided can be inspected by destructing
the syntax. Whether the syntax-case gets the original f or f* won't the
result be the same? (the result being applying the function `f' to 3).
Or are you saying that since `f' was not provided that
`make-rename-transformer' should not certify access to the syntax being
renamed?
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