On Tue, Oct 1, 2013 at 2:42 PM, Greg Hendershott <greghendersh...@gmail.com> wrote: > > 2. Plus it seems like it would be really unfortunate if carefully > choosing one of #'a or #'b were required -- because that would mean > `inner` couldn't be written to be usable by other macros independent > of knowing the origin of what they give to `inner`, right? I mean, > without knowing if a comes from `outer` or from the usage of `outer`, > and likewise for b, and therefore which of a or b to choose carefully.
Carefully choosing one _is_ required, and it _is_ really unfortunate. This is, in essence, why unhygenic macros are bad for composition. You have to pick something as the lexical context of your identifiers, and your choices are limited to (a) one of the syntax objects in your input or (b) whatever the previous expansion step was (that's what syntax-local-introduce does). Therefore, it's hard to compose them because they have to have a specific protocol for choosing identifier contexts, and if the protocols don't line up, everything becomes much more painful. Sam ____________________ Racket Users list: http://lists.racket-lang.org/users
