[plt-scheme] error reporting in MzScheme

From: Paulo Jorge de Oliveira Cantante de Matos (pocm at netvisao.pt)
Date: Thu Oct 23 05:50:54 EDT 2003

Strange, which version of DrScheme are you using? Which OS?

I just get the correct error message and it is not reversed. I'm running
205 in Linux, check it out: http://mega.ist.utl.pt/~pocm/Screenshot.png

Best regards,

Paulo Matos

On Thu, 2003-10-23 at 08:37, MicheleSimionato at libero.it wrote:
>   For list-related administrative tasks:
>   http://list.cs.brown.edu/mailman/listinfo/plt-scheme
> Having sent this message to comp.lang.scheme, they suggested me to ask for
> help to DrScheme mailing list, so here I am ;)
> -----
> I have decided to learn Scheme, so I have downloaded DrScheme which 
> seems to be the most newbie-friendly Scheme implementation (I think).
> The documentation is rather good and the framework nice enough,
> even if I would prefer less fancy graphics and more support
> for command line development (I work on Linux). For instance, 
> here are few things that bother me:
> 1. if I run mzscheme from the command line, there is no support for
>    the GNU readline library (I mean command history) so it is rather 
>    unusable;
> 2. I miss a command line tool such as perldoc or pydoc, to get
>    documentation on commands an built-ins;
> 3. the graphic environment does 2, but it is quite slow, at least 
>    on my old Pentium II laptop, and takes a lot of memory.
> 4. I can run mzscheme from emacs (GNU Emacs 21.2) but I am not
>    very satisfied with the default Scheme mode (I am sure there
>    are a better Scheme modes somewhere, isn't it?).
> All these are minor points and maybe there are workarounds about them; 
> however there is a major issue that really annoys me: 
> Nice error reporting is the most essential thing when you learn 
> a new language (and even when you already know the language, BTW).
> I want to have an informative message of what's going on, and especially
> I want to know the *line number* where the error occurred. Now, sometimes
> mzscheme reports the line number, sometimes not, particularly when I
> use macros. In this case mzscheme does return the error message 
> corresponding to the macro expansion (which is okay) but it does 
> *not* return the name of the invoked macro, not the line number where 
> the macro was defined: so it very difficult (especially in nested 
> expressions) to understand the origin of the error.
> Moreover, often the error message is reversed. For example
> executing the buggy code
> (define h (make-hash-table)) 
> (display "trying to get 'k\n")
> (hash-table-get h 'k)
> gives
> trying to get 'k
> k
> hash-table-get: no value found for key:
> whereas I should have got
> trying to get 'k
> hash-table-get: no value found for key: k
> The reversed error message really annoys me, and it gets even worse
> for buggy function calls (the arguments are printed before the
> error message). I am sure this is a buffering problem in stderr
> and probably it can be fixed. Is this a know issue?
> Also, I do I enable the readline support?
> TIA,
>                Michele Simionato

Paulo J. Matos : pocm at mega.ist.utl.pt
Instituto Superior Tecnico - Lisbon
Computer and Software Eng. - A.I.
 - > http://mega.ist.utl.pt/~pocm
        -> God had a deadline...
                So, he wrote it all in Lisp!

Posted on the users mailing list.