I think it's more a question of what a definition context is supposed to be, rather than how `syntax-local-bind-syntaxes` works.
When you create a new definition context, the context's bindings are visible only to expressions that are also in that context. The `test` form here creates a new definition context in much the same way as `(let () ...)`: (let () (let () (define x 1)) x) In other words, the final `x` really is out of the scope of the definition of `x`. At Mon, 05 Jan 2015 16:26:30 +0000, Spencer Florence wrote: > Progress is a new error! I don't think I understand how > syntax-local-bind-syntaxes is supposed to work. I extended the previous > program: > > #lang racket > (require (for-syntax syntax/parse)) > (define-syntax (test stx) > (syntax-parse stx > [(_ e) > (define ctx > (if (list? (syntax-local-context)) > (cons (gensym) (syntax-local-context)) > (list (gensym)))) > (define def-ctx (syntax-local-make-definition-context)) > (define expd (local-expand #'e ctx (list #'define-values) def-ctx)) > (define ids (syntax-parse expd [(def (id) _) (list #'id)])) > (syntax-local-bind-syntaxes ids #f def-ctx) > (internal-definition-context-seal def-ctx) > expd])) > (let () > (test (define x 1)) > x) > > And now I receive the error: `x: unbound identifier in module in: x` > Looking at the docs for `syntax-local-make-definition-context` it seems > like I need to provide it with the parent definition-context, but I'm not > sure how to get a hold of that. > > --spf > > On Mon Jan 05 2015 at 10:00:53 AM Matthew Flatt <mfl...@cs.utah.edu> wrote: > > > The error message is intended for "end users" and turns out to be > > misleading for the implementor of an internal-definition context. The > > documentation for `define-values` has essentially the same problem: it > > describes how `define-values` should work in an internal-definition > > context, but it doesn't say how the form interacts with `local-expand`. > > > > A `define-values` form will only expand in a module or top-level > > context. To implement an internal-definition context, you must expand > > only far enough to see `define-values` form; in other words, supply > > `#'define-values` in the stop list. Then, a partially expanded > > `define-values` form must be recognized and handled explicitly, with > > tools like `syntax-local-bind-syntaxes` or re-writing to > > `letrec-values`, as appropriate for the definition context. > > > > At Mon, 05 Jan 2015 14:49:03 +0000, Spencer Florence wrote: > > > Hey all, > > > > > > I'm trying to use 'local-expand', however it seems to think its never in > > a > > > definition context. For example: > > > > > > (require (for-syntax syntax/parse)) > > > (define-syntax (test stx) > > > (syntax-parse stx > > > [(_ e) > > > (define ctx > > > (if (list? (syntax-local-context)) > > > (cons (gensym) (syntax-local-context)) > > > (list (gensym)))) > > > (local-expand > > > #'e ctx null > > > ;; result is the same with this uncommented > > > #;(syntax-local-make-definition-context))])) > > > (let () > > > (test (define x 1)) > > > x) > > > > > > errors with a "define-values: not in a definition context in: > > > (define-values (x) 1)" > > > > > > Can anyone provide any insight into what is going on? > > > > > > --spf > > > ____________________ > > > Racket Users list: > > > http://lists.racket-lang.org/users > > ____________________ Racket Users list: http://lists.racket-lang.org/users
