I understand why the begin and [a a] work, but what I'm wondering is why the others didn't work. For example, why didn't `begin` work in my second example? Is the lexical information for the bindings just coming form somewhere really weird?
On Thu Nov 06 2014 at 5:18:59 PM Jay McCarthy <jay.mccar...@gmail.com> wrote: > The begin works because the macro use is at the top-level and the > thing gets pulled up and spliced in, I believe. > > The [a a] works because the second a is detected as a binder so it > gets matched up mark-wise with the second one rather than having them > erased? Hygiene? Marks? Dye packets? > > Jay > > On Thu, Nov 6, 2014 at 4:36 PM, Spencer Florence <spen...@florence.io> > wrote: > > Thanks! That fixed it! > > > > Although I'm still curious as to why the error happens in the first > place. > > > > On Thu Nov 06 2014 at 3:32:02 PM Alexander D. Knauth < > alexan...@knauth.org> > > wrote: > >> > >> I think I had a similar sort of problem about a year ago (I was at > either > >> RacketCon or a Hackathon that same weekend and Mathew Flatt figured it > out), > >> and the solution was changing (only-in path a) to (only-in path [a a]). > >> > >> #lang racket/load > >> ;;provider > >> (module T racket > >> (provide a) > >> (define a 1)) > >> ;; requirer > >> (module R racket > >> (require (for-syntax syntax/parse)) > >> (define-syntax (test-binding stx) > >> (syntax-parse stx > >> [(_ path) > >> #'(let () (local-require (only-in path [a a])) a)])) > >> (test-binding 'T)) > >> ;; go > >> (require ‘R) > >> > >> > >> On Nov 6, 2014, at 4:09 PM, Spencer Florence <spen...@florence.io> > wrote: > >> > >> > Hi All, > >> > > >> > I've been struggling to have a macro be given a path then require > >> > something from that path. The following code produces and "Unbound > >> > Identifier" error, although I would expect it to evaluate to 1. Could > >> > someone provide insight into what is going on? > >> > > >> > #lang racket/load > >> > ;;provider > >> > (module T racket > >> > (provide a) > >> > (define a 1)) > >> > ;; requirer > >> > (module R racket > >> > (require (for-syntax syntax/parse)) > >> > (define-syntax (test-binding stx) > >> > (syntax-parse stx > >> > [(_ path) > >> > #'(let () (local-require (only-in path a)) a)])) > >> > (test-binding 'T)) > >> > ;; go > >> > (require 'R) > >> > > >> > > >> > P.S. I attempted to do this with `dynamic-require,` but that failed > >> > because in my actual program `path` is sometimes `(submod "..")`, > which > >> > caused an error about not having a base path. > >> > > >> > ____________________ > >> > Racket Users list: > >> > http://lists.racket-lang.org/users > >> > > > > ____________________ > > Racket Users list: > > http://lists.racket-lang.org/users > > > > > > -- > Jay McCarthy > http://jeapostrophe.github.io > > "Wherefore, be not weary in well-doing, > for ye are laying the foundation of a great work. > And out of small things proceedeth that which is great." > - D&C 64:33 >
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