> I can't tell how the behavior you described differs from just providing the > variable from ark.rkt and requiring ark.rkt normally. Can you elaborate?
Wow. I'm not sure what misconceptions I was working under, but that works completely fine. And it looks like I can use something like defm from http://permalink.gmane.org/gmane.comp.lang.racket.user/13119 to hide the getters and setters. Thanks! That said, I'd still like to be able to enable the equivalent of the following in arc: #lang racket/load (define (test1) (displayln "a")) (define (test2) (test1)) (test2) (define (test1) (displayln "b")) (test2) Welcome to DrRacket, version 5.2.1 [3m]. Language: racket/load [custom]; memory limit: 128 MB. a b My current macro to handle top level assignment doesn't work in racket/load: #lang racket/load (require (for-syntax syntax/parse)) ; From Danny Yoo's arctangent ; https://github.com/dyoo/arctangent/blob/master/language.rkt ; Returns true if stx is an identifier that is lexically bound. (define-for-syntax (lexically-bound? stx) (let ([expanded (local-expand stx (syntax-local-context) #f)]) (cond [(and (identifier? expanded) (eq? #f (identifier-binding expanded))) #f] [else #t]))) (define-syntax (assign1 stx) (define-splicing-syntax-class binding-pair #:description "binding pair" (pattern (~seq var:id rhs:expr))) (syntax-parse stx [(_ p:binding-pair) (if (lexically-bound? #'p.var) #'(begin (set! p.var p.rhs) p.var) #'(begin (define p.var #f) (assign1 p.var p.rhs)))])) (assign1 a 5) When run, it never completes because lexically-bound? always returns false and recursion never terminates. If instead the assignment is in the body of a function, or in a module, it all works fine: (define (test) (assign a 5) a) Do these examples make my intent more clear? I'm not sure how to describe what I want correctly. -Nick On Mon, Jul 16, 2012 at 10:43 AM, Ryan Culpepper <r...@cs.utah.edu> wrote: > On 07/16/2012 03:35 AM, Nick Sivo wrote: >> >> Hi, >> >> I've been using the following awesome snippet to detect when >> identifiers are already bound: >> >> ; From Danny Yoo's arctangent >> ; https://github.com/dyoo/arctangent/blob/master/language.rkt >> ; Returns true if stx is an identifier that is lexically bound. >> (define-for-syntax (lexically-bound? stx) >> (let ([expanded (local-expand stx (syntax-local-context) #f)]) >> (cond >> [(and (identifier? expanded) >> (eq? #f (identifier-binding expanded))) >> #f] >> [else >> #t]))) >> >> Then I created a helper so I could call it at runtime: >> >> (define-syntax (arc-bound stx) >> (syntax-parse >> stx >> [(_ var:id) >> (if (lexically-bound? #'var) #'#t #'#f)])) >> >> That still worked great. Then I tried using racket/load: >> >> Welcome to DrRacket, version 5.2.1 [3m]. >> Language: racket/load; memory limit: 128 MB. >>> >>> (arc-bound a) >> >> #f >>> >>> (define a 5) >>> (arc-bound a) >> >> #f >>> >>> >> >> :( I've read through the docs on namespaces and the racket/load >> language source in an attempt to fully understand why racket/load is >> different, but I'm missing something. I've noticed that I can see 'a >> in (namespace-mapped-symbols), and have tried using that, but ran into >> (I think) phase issues. If there's a quick solution to this that I've >> missed, that's brilliant. > > > It works in DrRacket using #lang racket because the interactions occur in a > module namespace, but with #lang racket/load all interactions happen in an > ordinary namespace. That accounts for the differences in the results of > identifier-binding. > > >> Otherwise, my motivation to start making use of racket/load (really >> arc/load in my case), is to get access to global variables. If >> ark.rkt declares something at the module level, I need to be able to >> see it - the same copy of it - from other modules that require >> ark.rkt. What I'm trying now is to have ark.rkt be a real module >> written in arc, and then require it and load the rest of the arc files >> using the arc/load language so they all share the same module registry >> and the same ark.rkt. If there's some other, better way to do this, >> pointers will be quite warmly received. > > > I can't tell how the behavior you described differs from just providing the > variable from ark.rkt and requiring ark.rkt normally. Can you elaborate? > > Ryan ____________________ Racket Users list: http://lists.racket-lang.org/users
