--- Begin Message ---
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Subject: |
defect in guile with syntax transformation |
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Date: |
Sun, 2 Jun 2013 09:14:48 +0100 (BST) |
;; I think the below code exhibits a defect with guile 1.8.7.
;;
;; The `defrec' syntax transformer (defined below) does not behave
;; correctly within an imbedding `let' expression.
;;
;; The system is CYGWIN_NT-6.1-WOW64 WDFN00305859A 1.7.18(0.263/5/3)
;; 2013-04-19 10:39 i686 Cygwin
;;
;; Guile runs in GNU bash, version 4.1.10(4)-release (i686-pc-cygwin)
;; enable `define-syntax' functionality
(use-modules (ice-9 syncase))
;; OK
(let ( (n 99) )
(begin
(define
ev.OK? (lambda (x) (if (zero? x) #t
(od.OK? (- x 1)))))
(define
od.OK? (lambda (x) (if (zero? x) #f
(ev.OK? (- x 1))))))
(od.OK? 99))
;; OK, evaluates to #t
(define-syntax defrec
;; TYPE: syntax transformer.
;;
;; REQUIRES: (defrec . X) requires that X := ((S_1 V_1) ... (S_N
;; V_N)). The S_I are mutually distinct symbols. The V_J may contain
;; references to the S_I. On evaluation of any V_J the value bound
;; to a referenced S_I must not be needed.
;;
;; RETURNS: The value of the expression (begin (define S_1 #f)
;; ... (define S_N #f) (set! S_1 V_1) ... (set! S_N V_N)).
(syntax-rules ()
((_ (S V) ...)
(begin (define S #f) ...
(set! S V) ...))))
;; OK
(defrec
(ev.broken? (lambda (x) (if (zero? x) #t
(od.broken? (- x 1)))))
(od.broken? (lambda (x) (if (zero? x) #f
(ev.broken? (- x 1))))))
(od.broken? 99)
;; OK, evaluates to #t
(let ( (n 99) )
(defrec
(ev.broken? (lambda (x) (if (zero? x) #t
(od.broken? (- x 1)))))
(od.broken? (lambda (x) (if (zero? x) #f
(ev.broken? (- x 1))))))
(od.broken? n))
;; Produces an error message:
;; In standard input:
;; 14: 0* (let* ((n 99)) (defrec (ev.broken? #) (od.broken? #)) (od.broken?
n))
;; standard input:14:1: In procedure memoization in expression (let* (#)
(defrec # #) ...):
;; standard input:14:1: In file "standard input", line 14: Mixed definitions
and expressions in (defrec (ev.broken? (lambda (x) (if (zero? x) #t (od.broken?
(- x 1))))) (od.broken? (lambda (x) (if (zero? x) #f (ev.broken? (- x 1)))))).
;; Backtrace:
;; ABORT: (syntax-error)
--
Dr. M. Luedde, Rheinblick 26A, D-69226 Nussloch, Germany
+49-175-2779708, Skype: MirkoLuedde
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--- Begin Message ---
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Subject: |
Re: bug#14537: defect in guile with syntax transformation |
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Date: |
Tue, 04 Jun 2013 00:38:44 +0200 |
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User-agent: |
Gnus/5.130007 (Ma Gnus v0.7) Emacs/24.3 (gnu/linux) |
Hello,
"Dr. M. Luedde" <address@hidden> skribis:
> alright, I compiled guile 2.0.6 on my cygwin system.
>
> Given the amount and content of the warnings, it came as a surprise to me
> that the compilation apparently was successul and the resulting guile did
> process my testcase without the previously exhibited errors.
>
> I consider this defect report closed.
OK, thanks!
I know my answer may have sounded a bit frustrating, but it’s been more
than two years since 2.0 was released. It’s really a huge step forward
compared to Guile 1.8, and we hope people can appreciate it and find it
a good incentive to upgrade.
Ludo’.
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