This section http://www.r6rs.org/final/html/r6rs-lib/r6rs-lib-Z-H-1.html#node_toc_node_sec_12.7 begins by saying you can introduce a fixed number of identifiers by simply naming them, but when you don't know how many identifiers you will need you can use generate-temporaries. Now when you introduce temporary identifiers by simply naming them, they pick up the context of the transformer. So it seems there's an argument that generate-temporaries should behave analogously... (which would break Aziz's original definition of unbound?). What would be missing is a way to get at an empty context. Is there any way to remove define and syntax from the context of empty-ctxt in (library (foo) (export empty-ctxt) (import (only (rnrs) define syntax)) (define empty-ctxt (syntax here))) ?
On Fri, Jun 19, 2009 at 6:34 PM, Ramana Kumar<ramana.ku...@gmail.com> wrote: > I think this means that (car (generate-temporaries '(t))) is a > template id. So the next question would be whether R6RS, by saying > "Each temporary...is different from all other identifiers" is > implicitly saying that the context of the temporary is empty. Should > it be read that way? It's not clear what the context should be for a > generated temporary: two candidates in my mind are the empty context, > or the context of the call to generate-temporaries. > > On Fri, Jun 19, 2009 at 4:56 PM, leppie<xacc....@gmail.com> wrote: >> A template id is according to R6RS: >> >> From: >> http://www.r6rs.org/final/html/r6rs-lib/r6rs-lib-Z-H-13.html#node_chap_12 >> >> (syntax <template>) syntax >> >> Note: #’<template> is equivalent to (syntax <template>). >> >> A <template> is a pattern variable, an identifier that is not a pattern >> variable, a pattern datum, or one of the following. (etc ...) >> >> So, a template id is implicitly 'identifier?' >> >> Cheers >> >> leppie >> >> >> On Fri, Jun 19, 2009 at 8:22 AM, Ramana Kumar <ramana.ku...@gmail.com> >> wrote: >>> >>> > You're still using a syntax object in datum->syntax rather than a >>> > "template id". Does anyone know what a template id is? >>> >>> I have been guessing that a template id is the pattern variable called >>> "id" in either of the lines: >>> (syntax-case stx () >>> ((id . <>) <>) >>> (id <>)) >>> >>> Does that match anyone else's guess - maybe it was written somewhere >>> and I picked it up? >>> >>> On Fri, Jun 19, 2009 at 8:34 AM, Ramana Kumar<ramana.ku...@gmail.com> >>> wrote: >>> > You're still using a syntax object in datum->syntax rather than a >>> > "template id". Does anyone know what a template id is? >>> > >>> > Here's another version that works (I claim) (in Ikarus - I don't have >>> > the others) for all but two identifiers, and so may give a hint to >>> > what's going on. >>> > >>> > % cat unbound.scm >>> > (library (unbound) >>> > (export unbound-identifier?) >>> > (import (rnrs) (empty-ctxt)) >>> > (define (unbound-identifier? x) >>> > (free-identifier=? x (datum->syntax empty-ctxt (syntax->datum x))))) >>> > >>> > % cat empty-ctxt.scm >>> > (library (empty-ctxt) >>> > (export empty-ctxt) >>> > (import (only (rnrs) define syntax)) >>> > (define empty-ctxt (syntax empty-ctxt))) >>> > >>> > % cat t.ss >>> > (import (rnrs) (unbound)) >>> > (define-syntax if-unbound >>> > (lambda (x) >>> > (syntax-case x () >>> > [(_ (id) then else) >>> > (if (unbound-identifier? #'id) #'then #'else)]))) >>> > >>> > >>> > (define-syntax when-bound >>> > (syntax-rules () >>> > [(_ (id) e* ...) >>> > (if-unbound (id) (begin) (begin e* ...))])) >>> > >>> > (define-syntax when-unbound >>> > (syntax-rules () >>> > [(_ (id) e* ...) >>> > (if-unbound (id) (begin e* ...) (begin))])) >>> > >>> > (when-bound (let) >>> > (display "let is bound\n")) >>> > >>> > (when-bound (foo) >>> > cannot happen) >>> > >>> > (define-syntax q1 >>> > (syntax-rules () >>> > [(_) >>> > (begin >>> > (define q1* 12) >>> > (when-bound (q1*) (display "q1 is bound\n")))])) >>> > (q1) >>> > >>> > (when-bound (q1*) (display "q1* is bound\n")) >>> > >>> > (define-syntax q2 >>> > (syntax-rules () >>> > [(_ q2) >>> > (begin >>> > (define q2 12) >>> > (when-bound (q2) (display 'q2) (display " is bound\n")))])) >>> > >>> > (q2 quux) >>> > >>> > (define-syntax q3 >>> > (syntax-rules () >>> > [(_ q3 q4) >>> > (begin >>> > (define q3 12) >>> > (when-bound (q4) (display 'q4) (display " is bound\n")))])) >>> > >>> > (q3 quux1 quux1) >>> > (q3 quux2 quux3) >>> > >>> > (define a.cons 12) >>> > (when-bound (a.cons) (display "a.cons bound\n")) >>> > (when-bound (cons) (display "cons bound\n")) >>> > >>> > % cat t2.ss >>> > (import (unbound) (prefix (rnrs) r.)) >>> > (r.when (unbound-identifier? (r.syntax syntax)) >>> > (r.display "syntax unbound") >>> > (r.newline)) >>> > >>> > (r.when (unbound-identifier? (r.syntax define)) >>> > (r.display "define unbound") >>> > (r.newline)) >>> > >>> > (r.when (unbound-identifier? (r.syntax when)) >>> > (r.display "when unbound") >>> > (r.newline)) >>> > >>> > (r.when (unbound-identifier? (r.syntax foo)) >>> > (r.display "foo unbound") >>> > (r.newline)) >>> > >>> > % scheme-script t.ss >>> > let is bound >>> > q1 is bound >>> > quux is bound >>> > quux1 is bound >>> > a.cons bound >>> > cons bound >>> > >>> > % scheme-script t2.ss >>> > when unbound >>> > foo unbound >>> > >>> > On Fri, Jun 19, 2009 at 5:55 AM, Abdulaziz Ghuloum<aghul...@gmail.com> >>> > wrote: >>> >> >>> >> On Jun 18, 2009, at 4:42 PM, Ramana Kumar wrote: >>> >> >>> >>>> I already said I don't think it's 100% correct, but it works >>> >>>> on most implementations, and it satisfies your requirements. >>> >>>> If you don't want to use it, that's absolutely fine. >>> >> >>> >>> Oh I do want to use it =) But I also want to see the 100% correct >>> >>> version >>> >>> =P >>> >> >>> >> Okay. We ditch generate-temporaries which had underspecified >>> >> behavior. How about the following? [An idea clicked in my >>> >> head, I wrote it down, and it worked the first time, and when >>> >> I read the solution (2 lines really), it made no sense at all! >>> >> This is bizarre! Thanks Ramana! Maybe someone can explain it >>> >> to me. :-)] >>> >> >>> >> Aziz,,, >>> >> >>> >> PS. ypsilon still misses one test case >>> >> >>> >> $ ls b/* >>> >> b/bound.sls b/bound1.sls b/bound2.sls >>> >> >>> >> $ cat b/bound* >>> >> #!r6rs >>> >> (library (b bound) >>> >> (export unbound-identifier?) >>> >> (import (rnrs) (b bound1) (b bound2)) >>> >> (define (unbound-identifier? x) >>> >> (and >>> >> (free-identifier=? x (datum->syntax a.ctxt (syntax->datum x))) >>> >> (free-identifier=? x (datum->syntax b.ctxt (syntax->datum x)))))) >>> >> >>> >> #!r6rs >>> >> (library (b bound1) >>> >> (export a.ctxt) >>> >> (import (prefix (rnrs) a.)) >>> >> (a.define a.ctxt (a.syntax here))) >>> >> >>> >> #!r6rs >>> >> (library (b bound2) >>> >> (export b.ctxt) >>> >> (import (prefix (rnrs) b.)) >>> >> (b.define b.ctxt (b.syntax here))) >>> >> >>> >> $ cat t.ss >>> >> #!r6rs >>> >> (import (rnrs) (for (b bound) expand)) >>> >> >>> >> (define-syntax if-unbound >>> >> (lambda (x) >>> >> (syntax-case x () >>> >> [(_ (id) then else) >>> >> (if (unbound-identifier? #'id) #'then #'else)]))) >>> >> >>> >> (define-syntax when-bound >>> >> (syntax-rules () >>> >> [(_ (id) e* ...) >>> >> (if-unbound (id) (begin) (begin e* ...))])) >>> >> >>> >> (define-syntax when-unbound >>> >> (syntax-rules () >>> >> [(_ (id) e* ...) >>> >> (if-unbound (id) (begin e* ...) (begin))])) >>> >> >>> >> (when-bound (let) >>> >> (display "let is bound\n")) >>> >> >>> >> (when-bound (foo) >>> >> cannot happen) >>> >> >>> >> (define-syntax q1 >>> >> (syntax-rules () >>> >> [(_) >>> >> (begin >>> >> (define q1* 12) >>> >> (when-bound (q1*) (display "q1 is bound\n")))])) >>> >> (q1) >>> >> >>> >> (when-bound (q1*) (display "q1* is bound\n")) >>> >> >>> >> (define-syntax q2 >>> >> (syntax-rules () >>> >> [(_ q2) >>> >> (begin >>> >> (define q2 12) >>> >> (when-bound (q2) (display 'q2) (display " is bound\n")))])) >>> >> >>> >> (q2 quux) >>> >> >>> >> (define-syntax q3 >>> >> (syntax-rules () >>> >> [(_ q3 q4) >>> >> (begin >>> >> (define q3 12) >>> >> (when-bound (q4) (display 'q4) (display " is bound\n")))])) >>> >> >>> >> (q3 quux1 quux1) >>> >> (q3 quux2 quux3) >>> >> >>> >> (define a.cons 12) >>> >> (when-bound (a.cons) (display "a.cons bound\n")) >>> >> (when-bound (cons) (display "cons bound\n")) >>> >> >>> >> >>> >> $ IKARUS_LIBRARY_PATH='.' ikarus --r6rs-script t.ss >>> >> let is bound >>> >> q1 is bound >>> >> quux is bound >>> >> quux1 is bound >>> >> a.cons bound >>> >> cons bound >>> >> >>> >> $ plt-r6rs ++path . t.ss >>> >> let is bound >>> >> q1 is bound >>> >> quux is bound >>> >> quux1 is bound >>> >> a.cons bound >>> >> cons bound >>> >> >>> >> $ larceny -path . -r6rs -program t.ss >>> >> let is bound >>> >> q1 is bound >>> >> quux is bound >>> >> quux1 is bound >>> >> a.cons bound >>> >> cons bound >>> >> >>> >> $ ypsilon --sitelib=. --r6rs t.ss >>> >> let is bound >>> >> q1 is bound >>> >> quux is bound >>> >> quux1 is bound >>> >> a.cons bound >>> >> >>> >> >>> >> >>> >> >>> > >> >> >> >> -- >> http://codeplex.com/IronScheme >> http://xacc.wordpress.com >> >
