[plt-scheme] mzscheme and R6RS error

From: Matthew Flatt (mflatt at cs.utah.edu)
Date: Mon Dec 22 08:36:42 EST 2008

At Sun, 21 Dec 2008 15:11:00 +0100, Andreas Rottmann wrote:
> I'm playing with mzscheme's R6RS support, and found two issues with this
> simple test program:
> ---------mz-test.scm-----------
> #!r6rs
> (import (rnrs))
> (define (foo x y)
>   (when (> x y)
>     (error 'foo "x must be <= y" x y))
>   (- y x))
> (display (foo 1 2)) (newline)
> (display (foo 3 2)) (newline)
> --------mz-test.scm------------
> Running "mzscheme mz-test.scm", I get the following:
>        1
>        foo: x must be <= y
>         === context ===
>        /usr/local/stow/plt/lib/plt/collects/rnrs/base-6.ss:407:0: r6rs:error
> Note that the message is less useful than it could be, because the
> irritants (i.e. the values of x and y) are not included.

In SVN, I've added the irritants to the exception messages constructed
by `error' and `assertion-violation'.

> However, trying to get an error trace using "mzscheme -l errortrace
> mz-test.scm", I get no output at all.

You wanted

   mzscheme -l errrortrace -t mz-test.scm

When you run `mzscheme mz-test.scm', then `-t' is inserted
automatically, since there is no command-line flag before the first
argument. But when you provide `-l errortrace', then you have to be
more explicit about how to treat the "mz-test.scm" argument.


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