On Sat, Jun 4, 2011 at 3:17 PM, Jay McCarthy <[email protected]> wrote: > 2011/6/4 Carl Eastlund <[email protected]>: >> A question for the syntax certificate connoisseurs out there. The >> program below produces the following error message: >> >> compile: access from an uncertified context to unexported variable >> from module: "A" in: identity >> >> Why is the reference to identity from within the module that binds it >> illegal? Is that syntax object somehow not certified correctly, or >> does syntax-local-bind-syntaxes result in some illegal destructuring >> of its input? I imagine I can work around this by providing identity >> so that the certificate system ignores it, but I'd like to at least >> understand what's causing this error. >> >> #lang racket/load >> >> (module A racket >> (provide with-macro) >> (require (for-syntax racket/syntax syntax/parse)) >> (define-for-syntax (identity x) x) > > Isn't this a phase 1 binding?
Yup. >> (define-syntax with-macro >> (syntax-parser >> [(_ lhs:id rhs:expr e:expr) >> (define ctx (syntax-local-make-definition-context)) >> (syntax-local-bind-syntaxes (list #'lhs) #'(identity rhs) ctx) > > And this a phase -1 (template) use, which normally goes for the phase 0 > binding Nope. The second argument to syntax-local-bind-syntaxes is a compile-time (phase 1) expression. It is essentially equivalent to a syntax definition: (define-syntaxes [lhs] (identity rhs)) >> (internal-definition-context-seal ctx) >> (internal-definition-context-apply ctx #'e)]))) >> >> (module B racket >> (require 'A (for-syntax syntax/parse)) >> (with-macro thunk (syntax-parser [(_ e:expr) #'(lambda () e)]) > > And this is a phase 0 use? > > Is that the problem? Sadly, no. This would be easier to work out if it were a phase problem. The error message clearly says that identity refers to an unexported variable from A. If this were a phase problem, it should instead say that identity is unbound. --Carl _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
