[parenscript-devel] BLOCK/RETURN-FROM
Hi, I was wondering if the BLOCK/RETURN-FROM feature in PS intends to support the following case: (ps (defun foo () (flet ((bar () (return-from foo 42))) (bar)))) => WARNING: Returning from unknown block FOO "function foo() { var bar = function () { return 42; }; return bar(); };" In order to try and get around the warning, I tried this: (ps (defun baz () (block foo (flet ((bar () (return-from foo 42))) (bar))))) => WARNING: Returning from unknown block FOO "function baz() { var bar = function () { return 42; }; return bar(); };" but that didn't seem to work. Any ideas on how to achieve lexical return here? - Scott
At one point I had this implemented using try-catch unless Parenscript's compiler could prove (rather naively) that the return-from clause was always executed. I am usually way behind the official branch, and I'm not sure if my changes ever made it in, and if they did if this case is a bug. Anyway it would do something like function foo() { try { var bar = function () { throw { 'ps-return-foo341' : 42 }; }; bar(); } catch (e) { if ('ps-return-foo341' in e) return e['ps-return-foo341']; else throw e; }; verbose, but it should always work. other try-catch tricks allow lisp-style conditions, which I detailed in a post in this list within the year. in case of group interest the relevant code is available at https://github.com/gonzojive/paren-psos and https://github.com/gonzojive/parenscript Viva Parenscript! Red On Tue, Jun 7, 2011 at 11:40 PM, <sblist@me.com> wrote:
Hi,
I was wondering if the BLOCK/RETURN-FROM feature in PS intends to support the following case:
(ps (defun foo () (flet ((bar () (return-from foo 42))) (bar))))
=>
WARNING: Returning from unknown block FOO "function foo() { var bar = function () { return 42; }; return bar(); };"
In order to try and get around the warning, I tried this:
(ps (defun baz () (block foo (flet ((bar () (return-from foo 42))) (bar)))))
=>
WARNING: Returning from unknown block FOO "function baz() { var bar = function () { return 42; }; return bar(); };"
but that didn't seem to work. Any ideas on how to achieve lexical return here?
- Scott
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Red, While we're sort of on the topic... I recall that Vladimir liked your implementation of conditions in PS quite a bit. If you have a minute, would you care to summarize the basic idea? Alternatively I could just not be lazy and go look at it :) Daniel On Tue, Jun 7, 2011 at 12:07 PM, Red Daly <reddaly@gmail.com> wrote:
At one point I had this implemented using try-catch unless Parenscript's compiler could prove (rather naively) that the return-from clause was always executed. I am usually way behind the official branch, and I'm not sure if my changes ever made it in, and if they did if this case is a bug. Anyway it would do something like
function foo() { try { var bar = function () { throw { 'ps-return-foo341' : 42 }; }; bar(); } catch (e) { if ('ps-return-foo341' in e) return e['ps-return-foo341']; else throw e; };
verbose, but it should always work. other try-catch tricks allow lisp-style conditions, which I detailed in a post in this list within the year. in case of group interest the relevant code is available at https://github.com/gonzojive/paren-psos and https://github.com/gonzojive/parenscript
Viva Parenscript!
Red
On Tue, Jun 7, 2011 at 11:40 PM, <sblist@me.com> wrote:
Hi,
I was wondering if the BLOCK/RETURN-FROM feature in PS intends to support the following case:
(ps (defun foo () (flet ((bar () (return-from foo 42))) (bar))))
=>
WARNING: Returning from unknown block FOO "function foo() { var bar = function () { return 42; }; return bar(); };"
In order to try and get around the warning, I tried this:
(ps (defun baz () (block foo (flet ((bar () (return-from foo 42))) (bar)))))
=>
WARNING: Returning from unknown block FOO "function baz() { var bar = function () { return 42; }; return bar(); };"
but that didn't seem to work. Any ideas on how to achieve lexical return here?
- Scott
_______________________________________________ parenscript-devel mailing list parenscript-devel@common-lisp.net http://lists.common-lisp.net/cgi-bin/mailman/listinfo/parenscript-devel
_______________________________________________ parenscript-devel mailing list parenscript-devel@common-lisp.net http://lists.common-lisp.net/cgi-bin/mailman/listinfo/parenscript-devel
Generally, the idea is to implement a runtime function called SIGNAL in Parenscript and use JS's try/catch to work with the stack. Remember that handler-bind handlers are executed before the stack is unwound in an exceptional situation, while handler-case handlers are executed when already unwound. SIGNAL checks the available handlers and restarts. If a handler is found that accepts the error SIGNAL returns whatever that handler wants to return. Otherwise it throws a particular type of object (one with a property named 'ps-signal-p). HANDLER-CASE expands into a try-catch block where the catch inspects anything thrown for a 'ps-signal-p property and treats only such thrown objects as signals to be intercepted. That's the general idea. See https://github.com/gonzojive/paren-psos/blob/master/src/conditions-macrology... https://github.com/gonzojive/paren-psos/blob/master/src/paren/paren-conditio... Since conditions rest upon the type system, this is integrated with PSOS, the Parenscript version of CLOS. - Red On Wed, Jun 8, 2011 at 1:51 AM, Daniel Gackle <danielgackle@gmail.com>wrote:
Red,
While we're sort of on the topic... I recall that Vladimir liked your implementation of conditions in PS quite a bit. If you have a minute, would you care to summarize the basic idea? Alternatively I could just not be lazy and go look at it :)
Daniel
On Tue, Jun 7, 2011 at 12:07 PM, Red Daly <reddaly@gmail.com> wrote:
At one point I had this implemented using try-catch unless Parenscript's compiler could prove (rather naively) that the return-from clause was always executed. I am usually way behind the official branch, and I'm not sure if my changes ever made it in, and if they did if this case is a bug. Anyway it would do something like
function foo() { try { var bar = function () { throw { 'ps-return-foo341' : 42 }; }; bar(); } catch (e) { if ('ps-return-foo341' in e) return e['ps-return-foo341']; else throw e; };
verbose, but it should always work. other try-catch tricks allow lisp-style conditions, which I detailed in a post in this list within the year. in case of group interest the relevant code is available at https://github.com/gonzojive/paren-psos and https://github.com/gonzojive/parenscript
Viva Parenscript!
Red
On Tue, Jun 7, 2011 at 11:40 PM, <sblist@me.com> wrote:
Hi,
I was wondering if the BLOCK/RETURN-FROM feature in PS intends to support the following case:
(ps (defun foo () (flet ((bar () (return-from foo 42))) (bar))))
=>
WARNING: Returning from unknown block FOO "function foo() { var bar = function () { return 42; }; return bar(); };"
In order to try and get around the warning, I tried this:
(ps (defun baz () (block foo (flet ((bar () (return-from foo 42))) (bar)))))
=>
WARNING: Returning from unknown block FOO "function baz() { var bar = function () { return 42; }; return bar(); };"
but that didn't seem to work. Any ideas on how to achieve lexical return here?
- Scott
_______________________________________________ parenscript-devel mailing list parenscript-devel@common-lisp.net http://lists.common-lisp.net/cgi-bin/mailman/listinfo/parenscript-devel
_______________________________________________ parenscript-devel mailing list parenscript-devel@common-lisp.net http://lists.common-lisp.net/cgi-bin/mailman/listinfo/parenscript-devel
_______________________________________________ parenscript-devel mailing list parenscript-devel@common-lisp.net http://lists.common-lisp.net/cgi-bin/mailman/listinfo/parenscript-devel
This approach should be working in some code I just pushed (ae093417db848a1). I'm not checking whether return-from is executed, but rather taking the intersection of named blocks that can only be reached dynamically with the return-from tags that are contained lexically in those blocks, and generating the wrapping try-catch in the corresponding block places based on that. Happy hacking, Vladimir On Tue, Jun 7, 2011 at 2:07 PM, Red Daly <reddaly@gmail.com> wrote:
At one point I had this implemented using try-catch unless Parenscript's compiler could prove (rather naively) that the return-from clause was always executed. I am usually way behind the official branch, and I'm not sure if my changes ever made it in, and if they did if this case is a bug. Anyway it would do something like
function foo() { try {
var bar = function () { throw { 'ps-return-foo341' : 42 }; }; bar(); } catch (e) { if ('ps-return-foo341' in e) return e['ps-return-foo341']; else throw e; };
verbose, but it should always work. other try-catch tricks allow lisp-style conditions, which I detailed in a post in this list within the year. in case of group interest the relevant code is available at https://github.com/gonzojive/paren-psos and https://github.com/gonzojive/parenscript
Viva Parenscript!
Red
On Tue, Jun 7, 2011 at 11:40 PM, <sblist@me.com> wrote:
Hi,
I was wondering if the BLOCK/RETURN-FROM feature in PS intends to support the following case:
(ps (defun foo () (flet ((bar () (return-from foo 42))) (bar))))
=>
WARNING: Returning from unknown block FOO "function foo() { var bar = function () { return 42; }; return bar(); };"
In order to try and get around the warning, I tried this:
(ps (defun baz () (block foo (flet ((bar () (return-from foo 42))) (bar)))))
=>
WARNING: Returning from unknown block FOO "function baz() { var bar = function () { return 42; }; return bar(); };"
but that didn't seem to work. Any ideas on how to achieve lexical return here?
- Scott
_______________________________________________ parenscript-devel mailing list parenscript-devel@common-lisp.net http://lists.common-lisp.net/cgi-bin/mailman/listinfo/parenscript-devel
_______________________________________________ parenscript-devel mailing list parenscript-devel@common-lisp.net http://lists.common-lisp.net/cgi-bin/mailman/listinfo/parenscript-devel
participants (4)
-
Daniel Gackle -
Red Daly -
sblist＠me.com -
Vladimir Sedach