Re: [Chicken-users] Backslash-symbol changed from \ to \\ between 4.5.0 and 4.6.0
From: Peter Danenberg p...@roxygen.org Subject: Re: [Chicken-users] Backslash-symbol changed from \ to \\ between 4.5.0 and 4.6.0 Date: Wed, 6 Oct 2010 19:52:24 -0500 Quoth Felix on Prickle-Prickle, the 60th of Bureaucracy: This change is intentional. `\' is now a (single) escape character. The reading of keywords is indeed incomplete, yet. Ok; is the consensus, then, that I should escape all my backslashes in symbols with another backslash from 4.6.0 onwards? I agree with Peter Bex, though, that R5RS seems to be mum on the matter of backslashes in identifiers; according to 7.1.1 [1], in fact, these are the only explicitly allowed symbols in addition to letters and numbers: ! $ % * / : = ? ^ _ ~ + - . @ It might have been presumptuous of me to depend on the 4.5.0 behaviour; but it would be nice, on the other hand, to document the change somewhere. See the manual chaprter Non-standard read syntax - Escapes in symbols. cheers, felix ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Backslash-symbol changed from \ to \\ between 4.5.0 and 4.6.0
Quoth Felix on Setting Orange, the 61st of Bureaucracy: See the manual chaprter Non-standard read syntax - Escapes in symbols. Thanks for adding that, Felix. ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Backslash-symbol changed from \ to \\ between 4.5.0 and 4.6.0
On Tue, Oct 05, 2010 at 06:45:05PM -0500, Peter Danenberg wrote: Quoth Peter Danenberg on Pungenday, the 59th of Bureaucracy: [C]an we revert to the old behaviour, or can I revert locally by using `set-read-syntax!'? I didn't see any mention of this change to the reader in NEWS; was it intentional? There's been some work done on reading escaped/quoted literals to improve our SRFI-88 support (see ticket #322). It looks like the preliminary changes (the ticket hasn't been closed yet) have (accidentally?) been integrated: Chicken 4.5.0: #;1 '|foo|: foo #;2 Error: unbound variable: : Chicken 4.6.0: #;1 '|foo|: foo: I think the backslash shouldn't have any special meaning except in quoted symbols. AFAIK there's nothing in R5RS to support this, but then there's nothing in R5RS to support a backslash in symbols at all.. I can't find anything about this in R6RS either. I hope the WG1 will straighten this out ;) Cheers, Peter -- http://sjamaan.ath.cx -- The process of preparing programs for a digital computer is especially attractive, not only because it can be economically and scientifically rewarding, but also because it can be an aesthetic experience much like composing poetry or music. -- Donald Knuth ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Backslash-symbol changed from \ to \\ between 4.5.0 and 4.6.0
On Wed, Oct 06, 2010 at 09:35:33AM +0200, Peter Bex wrote: I think the backslash shouldn't have any special meaning except in quoted symbols. AFAIK there's nothing in R5RS to support this, but then there's nothing in R5RS to support a backslash in symbols at all.. On that note, perhaps you shouldn't be using '\ at all since it's not allowed by the RnRS (maybe Chicken should throw a syntax error) For something that works in all versions of Chicken, try quoting it: '|\\| Cheers, Peter -- http://sjamaan.ath.cx -- The process of preparing programs for a digital computer is especially attractive, not only because it can be economically and scientifically rewarding, but also because it can be an aesthetic experience much like composing poetry or music. -- Donald Knuth ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Backslash-symbol changed from \ to \\ between 4.5.0 and 4.6.0
From: Peter Bex peter@xs4all.nl Subject: Re: [Chicken-users] Backslash-symbol changed from \ to \\ between 4.5.0 and 4.6.0 Date: Wed, 6 Oct 2010 09:35:33 +0200 On Tue, Oct 05, 2010 at 06:45:05PM -0500, Peter Danenberg wrote: Quoth Peter Danenberg on Pungenday, the 59th of Bureaucracy: [C]an we revert to the old behaviour, or can I revert locally by using `set-read-syntax!'? I didn't see any mention of this change to the reader in NEWS; was it intentional? There's been some work done on reading escaped/quoted literals to improve our SRFI-88 support (see ticket #322). It looks like the preliminary changes (the ticket hasn't been closed yet) have (accidentally?) been integrated: This change is intentional. `\' is now a (single) escape character. The reading of keywords is indeed incomplete, yet. cheers, felix ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Backslash-symbol changed from \ to \\ between 4.5.0 and 4.6.0
From: Peter Danenberg p...@roxygen.org Subject: [Chicken-users] Backslash-symbol changed from \ to \\ between 4.5.0 and 4.6.0 Date: Tue, 5 Oct 2010 18:17:37 -0500 In 4.5.0, this sufficed to create a backslash symbol: '\ whereas in 4.6.0, we need: '\\ This change screws up a scheme-latex transformer I had written, unfortunately; can we revert to the old behaviour, or can I revert locally by using `set-read-syntax!'? You can use the `-no-symbol-escape' command-line option or the `symbol-escape' parameter. cheers, felix ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Backslash-symbol changed from \ to \\ between 4.5.0 and 4.6.0
Quoth Felix on Prickle-Prickle, the 60th of Bureaucracy: This change is intentional. `\' is now a (single) escape character. The reading of keywords is indeed incomplete, yet. Ok; is the consensus, then, that I should escape all my backslashes in symbols with another backslash from 4.6.0 onwards? I agree with Peter Bex, though, that R5RS seems to be mum on the matter of backslashes in identifiers; according to 7.1.1 [1], in fact, these are the only explicitly allowed symbols in addition to letters and numbers: ! $ % * / : = ? ^ _ ~ + - . @ It might have been presumptuous of me to depend on the 4.5.0 behaviour; but it would be nice, on the other hand, to document the change somewhere. Footnotes: [1] http://www.schemers.org/Documents/Standards/R5RS/HTML/r5rs-Z-H-10.html#%_sec_7.1.1 ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
[Chicken-users] Backslash-symbol changed from \ to \\ between 4.5.0 and 4.6.0
In 4.5.0, this sufficed to create a backslash symbol: '\ whereas in 4.6.0, we need: '\\ This change screws up a scheme-latex transformer I had written, unfortunately; can we revert to the old behaviour, or can I revert locally by using `set-read-syntax!'? ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Backslash-symbol changed from \ to \\ between 4.5.0 and 4.6.0
Quoth Peter Danenberg on Pungenday, the 59th of Bureaucracy: [C]an we revert to the old behaviour, or can I revert locally by using `set-read-syntax!'? Fortunately or unfortunately, this hideous hack suffices to bring back the 4.5.0 behaviour without permanently modifying the global read-table: (define (call-with-read-syntax char-or-symbol proc thunk) (let ((old-read-table (copy-read-table (current-read-table (dynamic-wind (lambda () (void)) (lambda () (set-read-syntax! char-or-symbol proc) (thunk)) (lambda () (set! current-read-table (lambda () old-read-table)) ;;; 4.5.0 behaviour: '\ = '\ (call-with-read-syntax #\\ (lambda (port) '\\) (lambda () (with-input-from-string '\\ read))) ;;; 4.6.0 behaviour: '\\ = '\ (with-input-from-string ' read) I didn't see any mention of this change to the reader in NEWS; was it intentional? ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
