parenscript-devel September 2012

parenscript-devel@common-lisp.net

3 participants
6 discussions

[parenscript-devel] Release 2.5 is out
by Vladimir Sedach 22 Sep '12

22 Sep '12

Hi everyone, I just uploaded the tarball for Parenscript 2.5. It should appear in a Quicklisp release soon. Let me know if there are any problems. Vladimir

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[parenscript-devel] Release this weekend
by Vladimir Sedach 19 Sep '12

19 Sep '12

Hello, Unless someone finds more bugs, I'm going to make a Parenscript release this weekend, which will go into the next Quicklisp release. If you have problems, the time to file bug reports is now. Happy hacking, Vladimir

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[parenscript-devel] Bug: amount of indentation when printing object literals varies
by Daniel Gackle 15 Sep '12

15 Sep '12

There seems to be some state in the PS compiler that changes its mind about how much indentation to use when printing an object literal over multiple lines. That is, when I change some PS code and recompile it, the indentation in unrelated areas sometimes changes, and when I reload PS, it goes back to the way it was. This makes it hard to do regression comparisons on the generated JS. I'm not quite sure how to formulate a test case for this, so am hoping the above description will trigger whatever insight is needed for a fix. Daniel

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[parenscript-devel] Bug: inconsistent gensym suffixes on what ought to be the same loop control variable
by Daniel Gackle 15 Sep '12

15 Sep '12

I just ran into a strange bug where the gensym'd suffixes on loop control variables change to the wrong thing. The bug appears to be triggered by a (RETURN) form inside a loop that has more than one FOR clause. For each extra clause, the suffixes increase by one. I haven't tried to track down the cause of the bug, but I did just push a failing test (LOOP-PARALLEL-CLAUSES-WITH-RETURN) to illustrate it. (defun-js foo () (loop :for i :from 0 :below 10 :for x = (* i 10) :when (> i 5) :do (return x) :collect i)) => (note added comments below): function foo() { return (function () { var collect3170 = []; var loopResultVarSet3171 = null; var loopResultVar3172 = null; for (var i = 0; i < 10; i += 1) { var x3171 = i * 10; if (i > 5) { loopResultVarSet3172 = true; // <---- suffix should be 3171, not 3172 loopResultVar3173 = x3171; // <---- suffix should be 3172, not 3173 break; }; collect3170.push(i); }; if (loopResultVarSet3171) { return loopResultVar3172; }; return collect3170; })(); }; Daniel

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[parenscript-devel] A simpler way to do multiple value return? (Was: PS test failures in 7be9b45)
by Daniel Gackle 15 Sep '12

15 Sep '12

Those test failures make sense now - thanks. Also, this comment reminded me of something: < the callee.caller property for functions, which multiple value return depends on > I dislike our implementation for multiple value return. Stuffing the values in callee.caller is complicated and doesn't feel right (I think I may have been the one who came up with it; it was a bad idea), plus it relies on one of the shakiest aspects if not of JS itself than certainly of the JS implementations. A simpler way occurred to me the other day and I'd like to know where it breaks. The argument goes like this: since JS is single-threaded and functions have to return synchronously, there can be only one function return in play at any given time, therefore there can be only one multiple-return-value list at any time, therefore why not just store it in a global variable? Say this variable is called *spillover*. Then this: (defun blah () (values 1 2 3)) (defun callblah () (multiple-value-bind (a b c) (blah) (+ a b c))) ...might compile to: function blah() { SPILLOVER = [2, 3]; return 1; }; function callblah() { var a = blah(); var b = SPILLOVER[1]; var c = SPILLOVER[2]; return a + b + c; }; There might be complicating factors that would make the JS more involved in practice, but I don't remember what they are. Apart from being so much simpler, this implementation has two advantages. First, it's "morally" better in Eugenia Cheng's sense (http://cheng.staff.shef.ac.uk/morality/morality.pdf). The multiple return values don't belong to caller or callee, but to the call itself. Caller and callee are functions that persist across many calls and ought not to have information about a specific call attached to them. That's why PS is forced to add ugly code to save the previous value attached to callee and restore it using a try/finally at the end. Second, it would fix a known problem. PS breaks when you have an interloper like FOO here: (defun blah () (values 1 2 3)) (defun foo () (blah)) (defun bar () (multiple-value-bind (a b c) (foo) (+ a b c))) BAR should return 6, and does in CL, but in PS it returns 1, because FOO doesn't return multiple values, so B and C are null and "1 + null + null" is 1 in JS. But the *spillover* hack would make BAR return 6. Could we get away with this, or what am I missing? Daniel On Tue, Aug 28, 2012 at 6:00 PM, Vladimir Sedach <vsedach(a)gmail.com> wrote: > Hi Daniel, > > Yes, those two failures in the eval test suite are expected. > CL-JavaScript doesn't have the callee.caller property for functions, > which multiple value return depends on. I wasn't sure where to comment > those tests out, so I left them in to remind myself to add > callee.caller to CL-JavaScript (I've already talked to Marijn > Haverbeke about that). > > Thank you, > Vladimir > > On Mon, Aug 27, 2012 at 11:58 PM, Daniel Gackle <danielgackle(a)gmail.com> > wrote: > > I've rebased my PS LOOP extensions [1] onto the latest commit > > (7be9b45) and recompiled Skysheet. The generated JS looks fine. There > > was one glitch that I'll report separately along with a workaround. > > Before pushing the LOOP extensions onto master, though, I want to > > update any relevant PS tests. Some will fail because the LOOP output > > has changed quite a bit. Unfortunately I'm also seeing failures when I > > run the tests in 7be9b45, which is prior to any of these LOOP > > changes. I've pasted the output below [2]. It doesn't look like these > > failures are related to work in ps-loop.lisp, so I'll just ignore them > > for the time being, but Vladimir can you please comment on whether you > > know about them or whether there's something unexpected going on? > > > > Daniel > > > > [1] These are the constructs FOR..OF and MAP..TO, plus a change to > > FOR..ON, that I described in my email to this list on April 11. They > > are currently sitting in the "loop" branch. Rebasing them was > > nontrivial because of Boris' additions to ps-loop.lisp, but it seems > > to have all gone ok. Boris, if you're reading this, please look out for > any > > regressions once I push these changes and let us know if you notice > > anything. > > > > [2] Running output tests: > > > ........................................................................................................................................................................................................................................................................................................................................................................................................................................ > > Did 424 checks. > > Pass: 424 (100%) > > Skip: 0 ( 0%) > > Fail: 0 ( 0%) > > Running package system tests: > > ......... > > Did 9 checks. > > Pass: 9 (100%) > > Skip: 0 ( 0%) > > Fail: 0 ( 0%) > > Running CL-JavaScript eval tests: > > ...........................f...............X...................... > > Did 66 checks. > > Pass: 64 (96%) > > Skip: 0 ( 0%) > > Fail: 2 ( 3%) > > Failure Details: > > -------------------------------- > > mv-return1 []: > > Unexpected Error: #<cl-js:js-condition #x30200155257D> > > [js] TypeError: undefined has no properties... > > -------------------------------- > > -------------------------------- > > dynamic-extent-function-return-values []: > > (funcall (if (typep #:g36204 'structure-object) #'equalp #'equal) > > #:g36204 (jsarray '(1 2 3))) was NIL.. > > -------------------------------- > > > > > > _______________________________________________ > > parenscript-devel mailing list > > parenscript-devel(a)common-lisp.net > > http://lists.common-lisp.net/cgi-bin/mailman/listinfo/parenscript-devel > > > > _______________________________________________ > parenscript-devel mailing list > parenscript-devel(a)common-lisp.net > http://lists.common-lisp.net/cgi-bin/mailman/listinfo/parenscript-devel > Those test failures make sense now - thanks. Also, this comment reminded me of something: < the callee.caller property for functions, which multiple value return depends on > I dislike our implementation for multiple value return. Stuffing the values in callee.caller is complicated and doesn't feel right (I think I may have been the one who came up with it; it was a bad idea), plus it relies on one of the shakiest aspects if not of JS itself than certainly of the JS implementations. A simpler way occurred to me the other day and I'd like to know where it breaks. The argument goes like this: since JS is single-threaded and functions have to return synchronously, there can be only one function return in play at any given time, therefore there can be only one multiple-return-value list at any time, therefore why not just store it in a global variable? Say this variable is called *spillover*. Then this: (defun blah () (values 1 2 3)) (defun callblah () (multiple-value-bind (a b c) (blah) (+ a b c))) ...might compile to: function blah() { SPILLOVER = [2, 3]; return 1; }; function callblah() { var a = blah(); var b = SPILLOVER[1]; var c = SPILLOVER[2]; return a + b + c; }; There might be complicating factors that would make the JS more involved in practice, but I don't remember what they are. Apart from being so much simpler, this implementation has two advantages. First, it's "morally" better in Eugenia Cheng's sense (http://cheng.staff.shef.ac.uk/morality/morality.pdf). The multiple return values don't belong to caller or callee, but to the call itself. Caller and callee are functions that persist across many calls and ought not to have information about a specific call attached to them. That's why PS is forced to add ugly code to save the previous value and restore it using a try/finally at the end. Second, it would fix a known problem. PS breaks when you introduce an interloper like FOO here: (defun blah () (values 1 2 3)) (defun foo () (blah)) (defun bar () (multiple-value-bind (a b c) (foo) (+ a b c))) BAR should return 6, and does in CL, but in PS it returns 1, because FOO doesn't return multiple values, so B and C are null and "1 + null + null" is 1 in JS. But the *spillover* hack would make BAR return 6. Could we get away with this, or what am I missing? Daniel

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[parenscript-devel] CASE keys in Parenscript vs. Lisp
by Boris Smilga 14 Sep '12

14 Sep '12

Hello. I've noticed that Parenscript has a different semantics from Lisp as regards keys of CASE clauses. Lisp assumes an implicit QUOTE in this context, so that a symbol used as CASE clause key matches a test-key which is EQL to the symbol, as opposed to its value. Parenscript, on the other hand, translates CASE forms to switch statements where symbol keys are used as identifiers. E. g. (let* ((foo 'bar) (bar 'foo) (x bar)) (case x ((foo) 1) ((bar) 2))) translates to (function () { var foo = 'bar'; var bar = 'foo'; var x = bar; switch (x) { case foo: return 1; case bar: return 2; }; })(); Note that the former evaluates to 1, the latter to 2. Now, is this a bug, or a feature? The section on CASE in the Parenscript Manual is actually misleading, whatever the answer. — B. Smilga.

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parenscript-devel September 2012