[plt-dev] syntax-case error messages

From: Robby Findler (robby at eecs.northwestern.edu)
Date: Mon Mar 29 16:15:54 EDT 2010

I think putting "syntax-case:" at the front of the error message is
the right thing (and that's a predictable thought, as I'm sure Matthew
is thinking right now since it means that macros that use syntax-case
to do their error checking will now have to do a better job). Maybe
the presence of Ryan's syntax parse library means we can go with this
nowadays, tho?

Robby

On Mon, Mar 29, 2010 at 2:06 PM, Jon Rafkind <rafkind at cs.utah.edu> wrote:
> Attached is a small patch for syntax-case that makes some error messages
> slightly more pleasant (at least to me).
>
> Old:
>> (syntax-case #'1 ())
> bad syntax in: 1
>> (syntax-case #'1 () 2)
> bad clause in: 2
>> (syntax-case #'1 () [2])
> bad clause in: (2)
>> (syntax-case #'1 () [2 2])
> bad syntax in: 1
>
> New:
>> (syntax-case #'1 ())
> syntax-case was unable to match any patterns in: 1
>> (syntax-case #'1 () 2)
> expected a list of clauses in: 2
>> (syntax-case #'1 () [2])
> expected 2 or 3 expressions in a clause in: (2)
>> (syntax-case #'1 () [2 2])
> syntax-case was unable to match any patterns in: 1
>
> There seems to be some disagreement with adding the name 'syntax-case' into
> the error message. I could live without that I guess, but it would be nice
> to change 'bad syntax' to something more informative, at least.
>
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