October 2010 - parenscript-devel - mailman3.common-lisp.net

[parenscript-devel] Patch: added JS label/break to PS
by Daniel Gackle 07 Dec '10

07 Dec '10

I just pushed a patch (authored by Scott) to implement JS's LABEL and BREAK in PS. (Note that this patch deprecates LABELED-FOR since you can get the same effect by combining LABEL and FOR. Was anybody using LABELED-FOR?) Here's an example: (label scope (foo) (when (bar) (break scope)) (blee)) => scope: { foo(); if (bar()) { break scope; }; blee(); }; I was astonished to discover recently that JS has supported this ability all along in the form of labeled statements and labeled breaks. I'd always assumed that to get explicit returns from an arbitrary scope, you'd have to resort to the ugly hack of muscling TRY/CATCH to do it, thinking that this was the closest JS counterpart. (See http://news.ycombinator.com/item?id=793092 for a thread in which several people believe this.) But it appears we were all wrong. What's not clear yet is how far this can be taken. Can you use it inside a nested local function to return immediately from the top-level function? That is one thing I've wanted for a long time. In the ideal case, LABEL/BREAK could be used as a base for implementing a proper BLOCK and RETURN-FROM in PS, something which we'd long believed to be impossible. One challenge is that in CL, RETURN-FROM can take a value, which becomes the value of BLOCK. In other words, BLOCK in CL is an expression while LABEL in JS is not. It seems, though, that most of this challenge has already been conquered with the development of implicit return in PS. The only thing you'd need to add is detecting when BLOCK is being used as an expression, declaring a gensymed variable and assigning whatever is happening inside BLOCK to that variable (much like implicit return already does with e.g. CASE), then put the variable in the expression position that BLOCK was in. It seems like this ought to work. It would also make things like this possible in PS: (1+ (case foo (:eleven 11) (:twelve 12))) Vladimir (and everybody), is the above clear? What do you think of it? Daniel

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[parenscript-devel] [PATCH] Define bit-shifting special forms >> and <<, and ASH as a macro.
by sblist＠me.com 06 Dec '10

06 Dec '10

I'm not sure how you feel about adding >> and << as special forms, but this seems to allow for a simpler implementation of ASH since it needs to do some higher-level transformations such as optimizing forms with a a constant COUNT argument along with avoiding multiple evaluation. Scott --- src/macros.lisp | 14 ++++++++++++++ src/package.lisp | 4 ++++ src/printer.lisp | 2 +- src/special-forms.lisp | 4 +++- 4 files changed, 22 insertions(+), 2 deletions(-) diff --git a/src/macros.lisp b/src/macros.lisp index 2014330..2c0c295 100644 --- a/src/macros.lisp +++ b/src/macros.lisp @@ -59,6 +59,20 @@ (define-ps-symbol-macro pi (getprop *math '*pi*)) +(defpsmacro ash (integer count) + (let ((count (ps-macroexpand count))) + (cond ((and (numberp count) (> count 0)) `(<< ,integer ,count)) + ((numberp count) `(>> ,integer ,(- count))) + ((complex-js-expr? count) + (let ((count-var (ps-gensym))) + `(let ((,count-var ,count)) + (if (> ,count-var 0) + (<< ,integer ,count-var) + (>> ,integer (- ,count-var)))))) + (t `(if (> ,count 0) + (<< ,integer ,count) + (>> ,integer (- ,count))))))) + ;;; Types (defpsmacro stringp (x) diff --git a/src/package.lisp b/src/package.lisp index 7921a37..92922e7 100644 --- a/src/package.lisp +++ b/src/package.lisp @@ -99,6 +99,10 @@ #:logxor #:lognot + #:ash + #:>> + #:<< + #:* #:/ #:rem diff --git a/src/printer.lisp b/src/printer.lisp index 73df146..5f119b7 100644 --- a/src/printer.lisp +++ b/src/printer.lisp @@ -169,7 +169,7 @@ vice-versa.") (defprinter js:post-- (x) (ps-print x)"--") -(defprinter (js:+ js:- js:* js:/ js:% js:&& js:\|\| js:& js:\| js:-= js:+= js:*= js:/= js:%= js:^ js:&= js:^= js:\|= js:= js:== js:=== js:!== js:in js:!= js:> js:>= js:< js:<=) +(defprinter (js:+ js:- js:* js:/ js:% js:&& js:\|\| js:& js:\| js:-= js:+= js:*= js:/= js:%= js:^ js:&= js:^= js:\|= js:= js:== js:=== js:!== js:in js:!= js:> js:>= js:< js:<= js:<< js:>>) (&rest args) (loop for (arg . remaining) on args do (print-op-argument op arg) diff --git a/src/special-forms.lisp b/src/special-forms.lisp index 6633b2f..5ca7a52 100644 --- a/src/special-forms.lisp +++ b/src/special-forms.lisp @@ -25,7 +25,9 @@ logior js:\| logxor js:^ lognot js:~ - ;; todo: ash for shifts + + >> js:>> + << js:<< throw js:throw array js:array -- 1.7.2.1

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[parenscript-devel] in-package and Parenscript compilation
by Alessio Stalla 06 Nov '10

06 Nov '10

Greetings, I'm approaching Parenscript and I must say I'm really impressed by this library. Kudos to the developers! But I find one thing missing: the Parenscript stream/file compiler does not understand in-package forms like the CL file compiler does; rather, it reads all the forms in the package which is current at the time it gets called. This makes it slightly inconvenient to compile Lisp files which need to be read in a certain package, and completely impossible to handle files which change *package* mid-file (which is generally not a good idea, but still it's possible in CL). I'm attaching a patch against src/compilation-interface.lisp to make the compiler behave like the CL one; comments are welcome. Regards, Alessio Stalla

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[parenscript-devel] Missing 'break' in CASE
by sblist＠me.com 06 Nov '10

06 Nov '10

It appears that some commit between ac408014 and b9dc8d1a (maybe 2f9fa1976a?) breaks the compilation of CASE forms in a function's tail position when some (but not all) branches in a body form contain a RETURN. PS> (ps (defun foo () (case x ("bar" (if y (return t) nil)) ("baz" nil)))) "function foo() { switch (x) { case 'bar': if (y) { return true; }; //----------------- missing break; here case 'baz': return null; }; };" Scott

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[parenscript-devel] Some notes on backward compatibility
by Vladimir Sedach 28 Oct '10

28 Oct '10

So there was a little bit of teh drama about Parenscript on Zach's blog today: http://xach.livejournal.com/274830.html?view=645006 I set the record straight, but as my reply makes a spiffy official Parenscript development policy that I hope everyone can agree with, I'm reposting it below: A general note about Parenscript: it's totally reasonable for new versions of Parenscript to implement ANSI CL functions and operators not implemented in previous versions. Another problem is that Parenscript started out with some non-ANSI features. By and large almost all of them turned out to be huge mistakes in practice, and are continually getting removed. Some of these can simply be put into the deprecated interface as macros - these will signal a warning at compile time advising how the deprecated functions/macros can be replaced with CL versions, but will still work. Some of these cannot be removed and will remain (for example, there is not really any way to express property access in ANSI Common Lisp, so that gets its own special form specific to Parenscript). However, one of these (symbol dot notation) turned out to be completely incompatible. Providing backwards compatibility for it would have meant replacing the entire CL reader for *any* code that generated Parenscript (even inline). As this feature made it impossible to implement things like proper scoping and was a continual source of bugs for PS code, I think removing it was the right choice. In conclusion, if you implement an ANSI CL function or special form that's not currently in Parenscript, be prepared that future versions of PS may re-implement it for you. You can preempt this surprise by contributing your code to Parenscript. Also, everyone is more than welcome to report bugs to the Parenscript mailing list: http://common-lisp.net/cgi-bin/mailman/listinfo/parenscript-devel Vladimir

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[parenscript-devel] ps hates my labels
by Dmitri Pavlenkov 28 Oct '10

28 Oct '10

What's wrong with my labels? PS[19]> (ps (defun fac (n) (labels ((f (n a) (if (< n 2) a (f (- n 1) (* n a))))) (f n 1))) ) *** - The object to be destructured should be a list with 0 elements, not ((- N 1) (* N A)). The following restarts are available: ABORT :R1 Abort main loop Break 1 PS[20]>

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[parenscript-devel] New Parenscript release: 2.2
by Vladimir Sedach 17 Oct '10

17 Oct '10

Hello, I've decided to make a new Parenscript release, 2.2. It includes mostly fixes. A couple of things have been deprecated. Implicit return should hopefully work better since last release. All reported unfixed bugs will go into the next release. Thinking about how to make expressionization work properly, and the latest bug reported by Scott, I realized that the way special forms work will need to change somewhat. Starting with 2.2, there will no longer be packaged releases for ASDF-Install (it's not any extra work making them, I just want to encourage people to use Quicklisp). Vladimir

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[parenscript-devel] Parenscript condition system implemented for PSOS
by Red Daly 01 Oct '10

01 Oct '10

I have added a Common Lisp-like condition system to the Parenscript Object System (PSOS). Parenscript now has HANDLER-BIND, HANDLER-CASE, RESTART-CASE, RESTART-BIND, INVOKE-RESTART, and SIGNAL. The patch that adds this is here: http://github.com/gonzojive/paren-psos/commit/6578ad223515dc2c1ddf49346f4ba… and totals about 200 lines, plus 200 lines of test cases. It could probably work without a type system at all, but it will require some runtime code no matter what. The whole PSOS system is backed by a test suite that uses CL-Spidermonkey. Take a look at PSOS here: http://github.com/gonzojive/paren-psos for more details. Enjoy! Red

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