<div dir="ltr">Thanks, I'll look into that. It's implemented in the C code, but it looks like it's effectively doing a combination of generate-temporary and syntax-local-lift-module-end-declaration. I don't think it gives me the option of creating two fresh identifiers with the same printed name in the same module and have them be immediately unique via free-identifier=?, as the binding would not have taken effect yet, so to speak. This is one of those cases where my life would be so much easier if I could relax any one of the constraints I'm working under. </div><div class="gmail_extra"> <div>Carl Eastlund</div> <div class="gmail_quote">On Fri, May 31, 2013 at 9:58 AM, Eric Dobson <<a href="mailto:eric.n.dobson@gmail.com" target="_blank">eric.n.dobson@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> If you replace all of your internal definition manipulation with (syntax-local-lift-expression #'#f), it passes your check.rkt. You don't have control over the names, but I'm guessing you could look into the implementation and see what it is doing to generate such names. <div class="HOEnZb"><div class="h5"> On Fri, May 31, 2013 at 8:32 AM, Carl Eastlund <<a href="mailto:cce@ccs.neu.edu">cce@ccs.neu.edu</a>> wrote: > I want a non-probabilistic guarantee of uniqueness, partly because I'd > rather not rely on something nondeterministic, and partly because in an > ideal solution, I'd like to have control over the printed names of these > identifiers. > > Carl Eastlund > > On Fri, May 31, 2013 at 9:27 AM, Eric Dobson <<a href="mailto:eric.n.dobson@gmail.com">eric.n.dobson@gmail.com</a>> > wrote: >> >> What does unique mean in this context? Does probabilistically unique >> work? If so could you form an identifier with the symbolic form >> "unique-id-"+UUID? >> >> On Fri, May 31, 2013 at 8:20 AM, Carl Eastlund <<a href="mailto:cce@ccs.neu.edu">cce@ccs.neu.edu</a>> wrote: >> > I'm having trouble creating identifiers that are unique with respect to >> > free-identifier=? and that survive marshaling to compiled code. The >> > normal >> > source of fresh identifiers, generate-temporaries, only guarantees they >> > are >> > unique with respect to bound-identifier=?. The obvious alternative, >> > gensym, >> > does not properly survive marshaling -- copies saved in different .zo >> > files >> > load as distinct identifiers. I've tried a few alternative methods, >> > none >> > more successful than either of these. >> > >> > Below, there are a few short files that show the difficulties and can be >> > used to test other methods. The first, fresh.rkt, contains the >> > procedure >> > used to create fresh identifiers. The file original.rkt creates a fresh >> > identifier at compile time. The file identical.rkt copies the >> > identifier >> > from original.rkt using quote-syntax. The file different.rkt creates >> > another fresh identifier at compile time. The file check.rkt checks >> > that >> > the identifiers from original.rkt and identical.rkt are >> > free-identifier=? to >> > each other, and that the identifiers from original.rkt and different.rkt >> > are >> > not free-identifier=? to each other. To run a test, first update >> > fresh.rkt >> > to use the appropriate method for creating identifiers, then run "raco >> > make >> > check.rkt". Some of the methods work when simply running "racket >> > check.rkt", but "raco make" marshals the identifiers to .zo files and >> > exposes more problems. >> > >> > Can anyone suggest an implementation that would work here? >> > >> > ;;;;; fresh.rkt >> > #lang racket >> > (begin-for-syntax >> > (require racket/syntax) >> > (define (fresh) >> > ;; does not guarantee free-identifier=? >> > #;(generate-temporary) >> > ;; does not survive marshaling >> > #;(gensym) >> > ;; also does not survive marshaling >> > (begin >> > (define id0 (datum->syntax #false 'fresh)) >> > (define ctx (syntax-local-make-definition-context)) >> > (syntax-local-bind-syntaxes (list id0) #false ctx) >> > (internal-definition-context-seal ctx) >> > (internal-definition-context-apply ctx id0))) >> > (provide fresh)) >> > >> > ;;;;; original.rkt >> > #lang racket >> > (require "fresh.rkt") >> > (define-syntax (macro stx) >> > (with-syntax {[name (fresh)]} >> > #'(begin-for-syntax >> > (define original (quote-syntax name)) >> > (provide original)))) >> > (macro) >> > >> > ;;;;; identical.rkt >> > #lang racket >> > (require "original.rkt") >> > (define-syntax (macro stx) >> > (with-syntax {[orig original]} >> > #'(begin-for-syntax >> > (define identical (quote-syntax orig)) >> > (provide identical)))) >> > (macro) >> > >> > ;;;;; different.rkt >> > #lang racket >> > (require "fresh.rkt") >> > (define-syntax (macro stx) >> > (with-syntax {[name (fresh)]} >> > #'(begin-for-syntax >> > (define different (quote-syntax name)) >> > (provide different)))) >> > (macro) >> > >> > ;;;;; check.rkt >> > #lang racket >> > (require "fresh.rkt" "original.rkt" "identical.rkt" "different.rkt") >> > (begin-for-syntax >> > (unless (free-identifier=? original identical) >> > (error 'fresh "~v != ~v\n" original identical)) >> > (when (free-identifier=? original different) >> > (error 'fresh "~v == ~v\n" original different))) >> > >> > -- >> > Carl Eastlund >> > >> > _________________________ >> > Racket Developers list: >> > <a href="http://lists.racket-lang.org/dev" target="_blank">http://lists.racket-lang.org/dev</a> >> > >> > </div></div></blockquote></div> </div>