Re: [Chicken-hackers] cond-expand and macros
On Thu, 2009-11-19 at 18:33 -0800, Kon Lovett wrote: Features are converted to keywords. The colon suffix is just the default read/print form; #:keyword is the context-independent form. The manual needs to document this; right now, one might have thought they were ordinary symbols given every example and description in the manual. 'cond-expand' uses a function that ensures the tested symbol is a keyword, so 'foo' '#:foo' are legal. That the expansion-environment of a 'syntax-rules' transformer doesn't recognize 'cond-expand' is a different problem. (Note that 'syntax- rules' in Chicken 3 is not a core expander.) So the bug is more or less that the self-evaluating nature of keywords doesn't work in the meta-environment for macro expansion, I assume. (Certainly that it goes differently in Chicken3+syntax-case is no mystery, since the old syntax-case egg needed to provide its own implementation of cond-expand anyway.) Thomas ___ Chicken-hackers mailing list Chicken-hackers@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-hackers
Re: [Chicken-hackers] cond-expand and macros
On Nov 20, 2009, at 10:05 AM, Thomas Bushnell BSG wrote: On Thu, 2009-11-19 at 18:33 -0800, Kon Lovett wrote: Features are converted to keywords. The colon suffix is just the default read/print form; #:keyword is the context-independent form. The manual needs to document this; right now, one might have thought they were ordinary symbols given every example and description in the manual. Please submit a bug report. 'cond-expand' uses a function that ensures the tested symbol is a keyword, so 'foo' '#:foo' are legal. That the expansion-environment of a 'syntax-rules' transformer doesn't recognize 'cond-expand' is a different problem. (Note that 'syntax- rules' in Chicken 3 is not a core expander.) So the bug is more or less that the self-evaluating nature of keywords doesn't work in the meta-environment for macro expansion, I assume. No, they are ordinary symbols (assuming the keyword read syntax is not present). The proffered symbol is converted to a keyword before comparison with the set of features. But this is performed by a procedure not the macro expander. The self-evaluating nature of keywords works in macros AFAIK. (Certainly that it goes differently in Chicken3+syntax-case is no mystery, since the old syntax-case egg needed to provide its own implementation of cond-expand anyway.) Thomas Best Wishes, Kon ___ Chicken-hackers mailing list Chicken-hackers@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-hackers
Re: [Chicken-hackers] cond-expand and macros
Thomas Bushnell BSG scripsit: The following code does not work: (define-syntax foo (syntax-rules () ((_) (cond-expand (chicken (display all good\n)) (foo) Calling (features) shows that the feature name is chicken:, not chicken. If you change the above to reference chicken:, all is well. This is not backward compatible and is still probably a bug, but at least it's a simple bug. On the other hand, (cond-expand (chicken (display all good\n))) does output all good right away. -- My corporate data's a mess! John Cowan It's all semi-structured, no less. http://www.ccil.org/~cowan But I'll be carefreeco...@ccil.org Using XSLT On an XML DBMS. ___ Chicken-hackers mailing list Chicken-hackers@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-hackers
Re: [Chicken-hackers] cond-expand and macros
On Nov 19, 2009, at 4:45 PM, Thomas Bushnell BSG wrote: Ok, so this is too weird by half. When I do (register-feature! 'foo), then the feature that is registered is foo:, despite what the actual manual says. And then, for some baroque reason, cond-expand matches foo and foo: (even though there is no foo feature registered, since it's actually foo:) and then, inside the context of a syntax-rules, suddenly cond-expand *doesn't* match foo, though it still matches foo:. Can I cry foul? Why doesn't register-feature! simply register the feature specified without this on-again-off-again colon magic? What is the point of adding a colon in the first place to the symbol name? Why is it magically removed again sometimes? Features are converted to keywords. The colon suffix is just the default read/print form; #:keyword is the context-independent form. 'cond-expand' uses a function that ensures the tested symbol is a keyword, so 'foo' '#:foo' are legal. That the expansion-environment of a 'syntax-rules' transformer doesn't recognize 'cond-expand' is a different problem. (Note that 'syntax- rules' in Chicken 3 is not a core expander.) Thomas On Thu, 2009-11-19 at 19:27 -0500, John Cowan wrote: Thomas Bushnell BSG scripsit: The following code does not work: (define-syntax foo (syntax-rules () ((_) (cond-expand (chicken (display all good\n)) (foo) Calling (features) shows that the feature name is chicken:, not chicken. If you change the above to reference chicken:, all is well. This is not backward compatible and is still probably a bug, but at least it's a simple bug. On the other hand, (cond-expand (chicken (display all good\n))) does output all good right away. ___ Chicken-hackers mailing list Chicken-hackers@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-hackers Best Wishes, Kon ___ Chicken-hackers mailing list Chicken-hackers@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-hackers
Re: [Chicken-hackers] cond-expand and macros
Kon Lovett scripsit: 'cond-expand' uses a function that ensures the tested symbol is a keyword, so 'foo' '#:foo' are legal. Fair enough. But in Chicken 4 syntax-rules macros, the non-keyword form doesn't match, only the keyword form. That makes no sense. It's not that cond-expand as a whole isn't being recognized, because it is; it throws an error because there is no match. -- The serene chaos that is Courage, and the phenomenon co...@ccil.org of Unopened Consciousness have been known to theJohn Cowan Great World eons longer than Extaboulism. Why is that? the woman inquired. Because I just made that word up, the Master said wisely. --Kehlog Albran, The Profit http://www.ccil.org/~cowan ___ Chicken-hackers mailing list Chicken-hackers@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-hackers
Re: [Chicken-hackers] cond-expand and macros
On Nov 19, 2009, at 7:15 PM, John Cowan wrote: Kon Lovett scripsit: 'cond-expand' uses a function that ensures the tested symbol is a keyword, so 'foo' '#:foo' are legal. Fair enough. But in Chicken 4 syntax-rules macros, the non-keyword form doesn't match, only the keyword form. That makes no sense. It's not that cond-expand as a whole isn't being recognized, because it is; it throws an error because there is no match. My hypothesis (I didn't check) is the non-keyword symbol is run thru a hygiene regimen; keywords cannot be identifiers so exempt. Maybe: (syntax-rules (foo) ((_ ?x ?y) (cond-expand (foo ... might do something useful. -- The serene chaos that is Courage, and the phenomenon co...@ccil.org of Unopened Consciousness have been known to theJohn Cowan Great World eons longer than Extaboulism. Why is that? the woman inquired. Because I just made that word up, the Master said wisely. --Kehlog Albran, The Profit http://www.ccil.org/~cowan Best Wishes, Kon ___ Chicken-hackers mailing list Chicken-hackers@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-hackers
