Squeak-dev January 1999

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143 participants
293 discussions

Re: Is Squeak tail recursive?
by Mark Wai 29 Jan '99

29 Jan '99

At 12:40 PM 1/28/99 GMT, you wrote: >Does the Squeak compiler generate properly tail recursive code? I believe the answer is no. It can support neither tail nor head resursion. It is because the current Block implementation in Squeak (i.e. BlockContext) is non-reentrant. The reason being the block object contains its own states (e.g. temporary variables, instruction pointer etc.) and therefore, multiple calls/activations of the same block object will not be possible since subsequent calls will overwritten the previous call's states. In Squeak, it will cause a walkback as soon as BlockContext detected that the execution has already been evaluated. The good news is, I believe that some people are working (or have already done) on fixing this problem (e.g. adding Closure object). For reference, take a look at VisualWork Smalltalk (www.objectshare.com). IMHO, It has one of the better Block/BlockClosure implementation (with optimization). Also refer to the blue book (www.ipa.net\dwight) for a detailed description of Smalltalk-80 based block implementation. -- Mark Wai Wator InnoVision

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Re: Order of precedence
by glenn 29 Jan '99

29 Jan '99

I think you're right--to do mathematical notation, you'd need mathematical precedence and standard function notation. In addition, you'd need to use conforming operators not #*, exponents denoted by graphic position not with bogus operators such as #^, elided operators for multiplication, horizontal lines for division, tall integrals, etc. etc. etc. That would be cool. Short of that, though, and you are asking the users to learn a necessarily incompatible (non-conforming) set of rules and you expect them to be able to go back and forth between their computer notation and their math notation. In that context, I don't see the relative precedence of #+ and #* as particularly significant, and my sympathies lie with simplicity. glenn At 10:45 PM 1/26/99 -0500, Ian Bicking wrote: >In message Tue, 26 Jan 1999 09:38:32 -0800, > glenn <krasner(a)objectshare.com> writes: >> c) cater to adults and children already computer-skilled who have >> preconceived notions set by some other computer languages which have >> multiple rules, one operator-based and the other left-to-right (or >> right-to-left or some such). > >I'm not saying that the normal, mathematical rules of precedence are easier >for children. Quite the contrary -- Smalltalk's simple left-to-right rule >is much more intuitive. This is the problem. A child who is introduced to >Smalltalk's system would likely have their intuition reinforced, making it >all the harder to learn the proper (mathematical notation) rules of >precedence. > >The fact of the matter is, mathematics says that 3+4*5=23. You can't change >that -- the mathematical conventions of the world are not going to be >changed because they are easier for the computer to parse. In a practical >matter, those conventions have been created because they *are* easier to >parse (for humans) in real-world situations. They lead to less parenthesis. >They group factors. They *are* aesthetic. > >Perhaps the real answer is to have a view of Squeak where the syntax is >fully mathematical. Where 3*sin(x^2+2) works. In this view a child could >learn mathematics. But it seems that a better solution could be made, one >that encompasses both needs (simplicity and conformity) instead of requiring >a break-away syntax. > >I bring this up because I've been looking at Logo, and one of the big >compromises they made in the syntax was to allow infix notation even though >it wasn't part of the Lisp tradition and sullied the syntax quite a bit. > >Now, this is all assuming that a goal of Squeak (distinct from Smalltalk) >is as a pedagogical tool. This is by no means necessarily true... though >it would be neat if Squeak could be used by children, that doesn't mean it >needs to be created for them to learn from it (though, of course, it is >impossible to seperate use from learning). Pedagogically, introducing >something that looks almost like proper mathematical expressions but isn't >is a bad thing to do. This is one reason (not necessarily a huge reason) >that I don't think Squeak is ready for children. > > > -- Ian Bicking > >

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Re: PWS, (s)Wiki & Proxies
by Chris Double 29 Jan '99

29 Jan '99

> Question: How does one operate behind a proxy that requires you to login > before connecting to the internet ? > (Using a proxy that does not require a loginID/password is no > problem) A few months ago I posted a similar question and got a reply from Thomas Morgan. He sent me a file in from Squeak 2.1 that fixed the problem for me (I was running 2.2). I have not tried it with 2.3 though. I've placed the file at: http://www.cnd.co.nz/squeak/HTTP.12Nov921pm.cs Thomas Morgan supplied it to me, so thank him for it, not me :-) >From his email message to me: >To use it: > > "Set and clear proxy authentication credentials" > " HTTPSocket clearProxyUserPassword. > HTTPSocket useProxyServerNamed: 'proxy.yourdomain.com' port: 8080. > HTTPSocket proxyUser: 'tmorgan' password: 'xxxxxxxx'" > > " HTTPSocket stopUsingProxyServer " > >You will find these code fragments in the 'examples' protocol, for the >class methods of HTTPSockets, in the method: > > proxyUserTestingComment > >The main trick here can be seen in the method > > proxyUser: userName password: password > >in the 'proxy settings' protocol of HTTPSocket, class methods. > >This method will show you what an authentication string looks >like, and how it is encoded. Pretty neat that there was already >a base 64 encoder in the image, eh? > >I just tested these changes with 2.2 with the proxy at work, but >please be careful; I haven't checked the small number of changes >that I made to make this go with 2.2 as carefully as should be done. Hope this helps, Chris.

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Re: Usability of Squeak on PDA's
by ohshima＠is.titech.ac.jp 29 Jan '99

29 Jan '99

> Even if you got Squeak to run on a Windows CE Palm-sized PC would it be > usable without a keyboard? It depends on the purpose for running Squeak. I wrote a software keyboard which does 'programming by example' style prediction in Squeak for keyboard-less PDAs. But it's still difficult to enter a certain amount program. I also wrote a programmable calculator for PDA. The user enters expressions by touching keys displayed on the screen and the calculator evaluate the expresison and display the answer. Because the tokens that would appear in the expressions are (basically) limited, so the limited number of the keys is ok, and entering the expressions is confortable enough. The CPU performance on the PDA is almost ok, and it will follow the steep increase which the CPUs for desktops have been shown. The limited memory capacity and the area of the display device is the biggest problem for 'real' applications. OHSHIMA Yoshiki Dept. of Mathematical and Computing Sciences Tokyo Institute of Technology P.S. Did anyone design small fonts (around 5-7 dot high)?

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Squeak talk at Smalltalk conference
by Ivan Brusic 29 Jan '99

29 Jan '99

There is going to be a session about Squeak at the Smatlltalk Solutions '99 conference in NYC. From: http://www.smalltalkconference.com/html/conference/sessions3.shtml Squeak: A New Generation Open-Source Smalltalk Based on, and developed in Smalltalk, Squeak is a development environment that offers an Integrated Development Environment, a sophisticated GUI, Internet support, and a VM written in a subset of Smalltalk that can be translated to C to create new VMs. In this session, history, significance and features of Squeak will be discussed with examples. Level: Intermediate to Advenced -- Ivan Brusic | "Computers are nothing but a perfect Graduate Student | illusion of order" - Iggy Pop College of Computing & GVU Center | Georgia Institute of Technology | E-mail: ivan [at] cc.gatech.edu

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Updates to Release 2.3
by Dan Ingalls 29 Jan '99

29 Jan '99

Folks - I have just distributed 8 new updates to Squeak 2.3. Many thanks for your useful contributions. Here follows a summary list... - Dan ------------------- 603share-rename-tkIV 604FindAgain-tkIU 605diffInChangeList-sw -- Scott Wallace -- 27 January 1999 Deploys Andreas's diff function in changelist & versions browsers. For a versions browser, each version shows its diffs from the preceding version. For a changelist browser, diffs from the in-memory versions, if any, are shown. New preference #showDiffsInChangeList governs whether or not the diff feature should be used." 606ThreeChanges-di -- Dan Ingalls -- 28 January 1999 Changes the response of 'browse versions' commands when there is only one version. A recent change made it simply say 'No older versions', but this was bad if you wanted to see, eg, the version stamp, or just a clean copy of the method. The new reponse is similar, but offers the option to see the only version anyway. Limits the speed of the zoom transistion (between projects) to 500 ms. Machines are getting fast enough that you can't see a full-speed zoom. Increases the composition box of a textMorph with no container. The previous limits had caused a false end in very long paragraphs, as when examining a megabyte long file in the FileList. The new limit is still finite, but corresponds to the practical limit of single paragraphs. Also updates the text of the command-key help window. 607Time-class-readFrom -- Bert Freudenberg -- 608ServerDirectory-entries -- Leandro Caniglia -- 609IPaddress-mdr -- Michael Rutenberg (mdr(a)scn.org) -- 27 January 1999 Corrects a small bug that prevented the lookup of host names which begin with a digit, such as 100000jobs.de Host names lookup will now be fully compliant with RFC 1123 section 2.1" 610ScamperFixes -- Tim Olson -- 22 January 1999 Fixes for 2 bugs discovered when browsing various web pages with Scamper PluggableListMorph>>selectionIndex: This fix prevents an out-of-bounds error when a ListMorph with a non-zero default index is initialized without initializing the list at the same time. HTTPSocket class>>httpGetDocument:args:accept:request: Added missing parenthesis around (self argString:args) when concatenating to the page string. 611DigitBufferNot -- Dan Ingalls -- 28 January 1999 Removes the unused class variable 'DigitBuffer' from SmallInteger. Suggested by Luciano Notarfrancesco

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bug report/fix
by Leandro Caniglia 29 Jan '99

29 Jan '99

<aPolygon>drawOn: aCanvas uses the receiver's borderColor to draw the arrow(s), if any, on aCanvas. The method fails to take into account that borderColor could be #raised or #inset. Here is a simple fix. Leandro Content-Type: application/octet-stream; name="PolygonMorph-drawOn.st" Content-Disposition: attachment; filename="PolygonMorph-drawOn.st" Attachment converted: Anon:PolygonMorph-drawOn.st (????/----) (000065B9)

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Re: Order of precedence
by bickiia＠yang.earlham.edu 29 Jan '99

29 Jan '99

In message Wed, 27 Jan 1999 20:40:23 +0100, Joachim Durchholz <joachim.durchholz(a)munich.netsurf.de> writes: >Eliot & Linda Miranda wrote: >> What are the relative recidences of + - * / \\ // < <= > >= = ~= ? > > From my above remarks, a highest-to-lowest precedence table is actually > easy to construct, and actually observed in multi-precedence languages > like C and Prolog: > > Exponentiation ^ (is this actually in Smalltalk?) > Multiplicative * / // \\ > Relational < <= > >= > Equality = == ~ ~~ > Assignment := This is where I've always seen the benefit of the Smalltalk syntax. If there's precedence (besides, of course, left-to-right) then it wouldn't really be fair to make precedence something magical about the base syntax and inaccessable to user-created operators. That the user/programmer is a peer of the language designer/library creator is one of the most important things about Smalltalk, IMHO. But if everyone can play with precedence, the syntax gets out of hand. If you aren't very familiar with all the operators used (and perhaps the context as well, since they are just messages) it becomes difficult to read code. The precedence of a single operator could change the meaning of an entire statement. (I get the impression that this was a capability and problem of Smalltalk 76...?) So you have the Algols, which give power to the language designer, and Lisps, which give up on infix entirely. I like that Smallktalk figured out a way to do infix without tyranny. I'm just wondering or hoping that there might be some way that does everything right without making compromises. That's what rethinking is about -- everyone knows the compromises, languages have divided and families have been formed around those compromises. But maybe there's a different way of thinking about it that lets you have it all. IMHO, that's what Squeak (not necessarily Smalltalk) is supposed to be about. >> Or is maintaining readability less important than attempting to >> provide an inaccurate simulation of mathematical notation (e.g. * >> instead of adjacency)? > > Bah. No rethorics please. I understand you are accustomed to Smalltalk > tradition and don't want to learn new tricks for little gain, but that > doesn't necessarily mean that the position of anybody with a different > opinion is so ridiculous as you present it here. I must say I too was quite annoyed with the nit-picking that "*" is not the same as adjacency. Be it an x, a dot, or * doesn't matter -- that confuses no one. Changing the symbols is unimportant -- changing the semantics *is* important. >> I think very strongly that the current design of the infix rules is >> better than any other programming language I've used, that its easier >> to teach, that its easier to learn, and easier to use. I'd like to point out that when I started this thread, I never meant that it was too hard to learn Smalltalk's left-to-right rule. Only that it could confuse children who will later have to learn about the order of precedence. Maybe the whole issue could be generalized and politicized: do we accept outside conventions? Is Squeak a world of its own? If it is, is that being high-minded or egotistic? But those aren't really the questions I wanted to ask... I was just hoping there was some way that I couldn't see that would allow precedence without making Smalltalk into C. Sigh. -- Ian Bicking

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Re: Remote desktops under Squeak?
by Bob Hartwig 29 Jan '99

29 Jan '99

Are there any plans for full-blown data conferencing, including shared whiteboards and remote control? How about IP Telephony? At 12:34 PM 1/28/99 -0800, you wrote: >>I have a question...what is the purpose of the 'remote' connections under >>Squeak (in morphic projects)? The most I can get it to do is to share pointers >>between two machines running squeak, but the desktop is not shared (like Self). >> >>Another thing I noticed: I could only 'share' between a Windows Squeak and a >>Unix squeak...Unix to Unix did not work (produced a debug window). > >This was part of a quick hack that John and I did for OOPSLA '97. The idea is: > >As long as a bunch of machines start running the exact same configuration of Morphic, and each runs all the other remote hands, then in theory, they will all remain synchronized without any need for serious data synchronization. In other words it is possible to run a multi-user painting program with no more net bandwidth than mouse coordinates, because the high bandwidth work (painting the screen) is being done locally on each machine (we demoed this at OOPSLA). Similarly we lashed up a techno music generator that could play music in real time with multiple users, the key being that the only info that had to be transmitted were the mouse events that implied that a given sound object was being picked up or dropped in a given place. > >It's clear that there are ways that this will fail, and it's clear what more is needed to do more with multiple users, but this is the answer to your question about where this feature came from and what it does. > >I can't tell you anything about why it works or doesn't with different platform combinations -- I'm amazed it still works at all ;-) > > - Dan > > > >

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Re: JIT compiler
by Ian Piumarta 28 Jan '99

28 Jan '99

> For those of you how a interested how JIT compilers > can be implemented. [...] ftp://tr-ftp.cs.berkeley.edu/pub/tech-reports/csd/csd-94-792/all.ps http://www.cs.cmu.edu/~spot/nitrous.ps http://www.cs.indiana.edu/proglang/dynamo ftp://ftp.cs.washington.edu/tr/1991/11/UW-CSE-91-11-04.PS.Z http://www.cs.washington.edu/research/dyncomp http://www.cs.washington.edu/research/projects/unisw/DynComp/www/ http://www.mit.edu:8001/afs/cs.cmu.edu/project/fox/mosaic/papers/mleone-rtc… http://www.pdos.lcs.mit.edu/~engler/vcode-pldi.ps http://www.pdos.lcs.mit.edu/tickc http://www.softlab.is.tsukuba.ac.jp/~chiba/oopsla98/proc I don't think the following are available online... C. Chambers, D. Ungar and E. Lee, An Efficient Implementation of Self, a Dynamically-typed Object-Oriented Language Based on Prototypes. ACM SIGPLAN Notices, 24(10):49--70, October 1989. Dawson Engler and Todd Proebsting, DCG: An Efficient, Retargetable Dynamic Code Generation System. ACM SIGPLAN Notices, 29(11):263--273, October 1994. Ali-Reza Adl-Tabatabai, Michal Cierniak, Guei-Yuan Lueh, Vishesh M. Parikh and James M. Stichnoth, Fast, Effective Code Generation in a Just-In-Time Java Compiler. ACM SIGPLAN Notices, 33(5):280--290, June 1998. Ian

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