On Tue, Sep 6, 2011 at 8:05 PM, John Clements <cleme...@brinckerhoff.org> wrote: > > On Aug 18, 2011, at 5:32 AM, Sam Tobin-Hochstadt wrote: > >> >> Yes, I understand why this happens. As I see it, there are a few >> possibilities: >> >> 1. The expander should check for duplicates, in some fashion. >> 2. This idiom is problematic, in the case where `stx' is both the >> input and used for the syntax properties of the output. >> 3. Macros may freely duplicate syntax properties. >> >> All of these have drawbacks, but (3), which you are suggesting, means >> either that syntax properties can only be used to specify idempotent >> information or that the non-idempotent ones need to have some >> *explicit* means by which equal elements can be distinguished, which >> must be part of the API of that syntax property. >> >> If we think this is how syntax properties ought to work, then we >> should add something to the documentation making this clear, and we >> should recognize that it's a limitation. > > Would syntax-property guards solve this problem?
I don't really see how. What are you thinking of? -- sam th sa...@ccs.neu.edu _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/dev
