Awesome! Thanks, that works for what I'm doing. On Mon Jan 05 2015 at 2:47:43 PM Matthew Flatt <mfl...@cs.utah.edu> wrote:
> That turns out to be tricky. I've enclosed an implementation, but it > works only for units that have no imports. > > At Mon, 05 Jan 2015 17:21:37 +0000, Spencer Florence wrote: > > What I'm trying to do is capture all lifts inside a unit body, instead of > > having them propagating to the top level. > > > > If I understand what you mean by "add internal-definition context to the > > bindings listed in `exports`", I can't do that because I need to capture > > any lifts inside the unit body, but a `(local-expand/capture-lifts > #'(unit > > ...))` would put them outside. But maybe I miss understand you. > > On Mon Jan 05 2015 at 12:10:53 PM Matthew Flatt <mfl...@cs.utah.edu> > wrote: > > > > > I'm not really clear on what you're trying to do. One way to explain > > > more might be to explain how `test` is meant to differ from `begin`. Or > > > maybe you can say why it doesn't work to add the internal-definition > > > context to the bindings listed in `exports` (i.e., to bring everything > > > into the definition context). > > > > > > At Mon, 05 Jan 2015 16:44:10 +0000, Spencer Florence wrote: > > > > Is there any way to have the `test` macro work more like `begin`? > > > > > > > > What I am trying to accomplish is something like: > > > > > > > > (define-syntax (make-my-unit stx) > > > > (syntax-parse stx > > > > [(e ...) > > > > (with-syntax ([body (local-expand/capture-lifts stx > <something>)]) > > > > #'(unit (imports ...) (exports ...) body))])) > > > > > > > > Where the defines in #'(e ...) are visible to `unit` so that they > can be > > > > used for exports. > > > > > > > > --spf > > > > On Mon Jan 05 2015 at 11:32:46 AM Matthew Flatt <mfl...@cs.utah.edu> > > > wrote: > > > > > > > > > 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 > > > > > > > > > > > > > > >
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