Squeak-dev December 1998

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125 participants
236 discussions

As We May Read
by Mark Guzdial 31 Dec '98

31 Dec '98

In this month's IEEE Computer, an article by Bill Schilit and his colleagues at Fuji-Xerox and Xerox PARC entitled "As We May Read: The Reading Appliance Revolution," begins: "In the 1970's, Alan Kay and his colleagues at Xerox PARC envisioned a dynamic, interactive book. Now, nearly 30 years later, that vision has become a reality." Wow, I think, they've got DynaBooks! Well, no, not really. Well, actually, they're not even trying. Their goal is to make electronic paper. The article is all about supporting reading, providing searching/linking/organizing, annotation support, battery weight and screen resolution, doing formatting right, etc. It's all good stuff, but... None of the stuff about "metamedia" is there, which was in the original "Personal Dynamic Media." The idea that a computer could be movies + graphics art + well-formatted text + truly interactive computational elements was key to the notion of a metamedium, which is what DynaBook documents were supposed to be, I thought. All the text in the AWMR piece looks like it could be from the Web. They don't talk about creating the next printing press, nor about what it might be like to create truly interactive documents. This is about creating something that's like paper, but it's electronic, and thus searchable/linkable/filterable/etc-able. But maybe I'm reading it wrong. Do others on this list know this work? Is the eventual goal to actually create something like the DynaBook, or is does this paper really reflect the realization of this vision? Mark -------------------------- Mark Guzdial : Georgia Tech : College of Computing : Atlanta, GA 30332-0280 (404) 894-5618 : Fax (404) 894-0673 : guzdial(a)cc.gatech.edu http://www.cc.gatech.edu/gvu/people/Faculty/Mark.Guzdial.html

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Re: Float Question
by Tim Olson 31 Dec '98

31 Dec '98

>>> 52 bits of significand. > >As I sit listening to Professor Kahan on tape while reading "52", I see >on the other monitor the number 53. The larger number is actually the >right one, despite the fact that 53+11+1 > 64, because, for normal >numbers, the leading bit of the significand is boring. It is always on. >That's what normalization does, after all. Since it is so boring, we >need not even store it. Yes, you are right. To be precise I should have said 52 bits of "fraction", not "significand", although you'll find that many texts also use these two words interchangeably, adding to the confusion. Excerpt from the PowerPC Architecture Manual: ---- Representation of numeric values in the floating-point formats consists of a sign bit (S), a biased exponent (EXP), and the fraction portion (FRACTION) of the significand. The significand consists of a leading implied bit concatenated on the right with the FRACTION. This leading implied bit is 1 for normalized numbers and 0 for denormalized numbers and is located in the unit bit position (i.e., the first bit to the left of the binary point). ---- -- tim

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Re: Another mainstream article about Squeak at PCWeek Online
by Dan Shafer 31 Dec '98

31 Dec '98

Speaking both as a Squeaker of sorts and as a techno-journalist who has chosen not yet to discuss much about Squeak publicly yet, I can tell you that there is pent-up demand out there for information about any language that will solve real-world problems faced by the people building the Internet and the Web. I mentioned Squeak almost in passing on my "Project Heresy" radio show at CNET Radio a few weeks ago and was literally inundated with requests for followup information. I positioned Squeak as a viable platform-independent development language with a graphical interface that had the promise of making Linux more viable as a deplooyment platform. I've talked with the Squeak team once or twice about doing a column or a feature about Squeak and the Web/Internet but they feel -- and I agree -- that we're not yet ready for prime time attention. But I have to tell you, the itch gets stronger all the time. "Andrew C. Greenberg" wrote: > > > What I'm concerned will happen is that sixteen zillion Java programmers will > > see this and think, "Kewl! A new way to do <applets/beans/whatever>!!". > > They'll flood the Squeak servers with downloads, will get turned off when it > > doesn't look-and-feel like C or VB, has no "sandbox" (litter box? :-), > > doesn't do <applets/beans/whatever>, doesn't "interoperate" with > > Java/VBScript/whatever, and the next article written will be titled "Squeak > > Fails To Live Up To Promise". <sigh> Journalists... > > Fear not -- this is the virtue of open source -- if it isn't what they > want, its their fault for not making it so. As a CS/hacker sophisticate, > yet Softalk newbie, I shared these urges/instincts, but owing to my general > deference, thought I'd study the matter for awhile before making such > overarching attempts to inject an unstudied aesthetic into a clearly > well-developed culture. > > But trust me, more ideas are better -- even if they are bad ideas. That's > the whole notion of the Bazaar. The bad ideas will die out, and the good > ones -- including those synthetic "make this more like that" ideas that > aren't bad ideas will evolve into the "next great thing." > > Have faith -- there are great minds out there, and Squeak is for everyone. -- Dan Shafer, Looking at Technology from Every Angle Home Page: http://www.gui.com - Email: dan(a)gui.com There is nothing more powerful than an idea whose time has come.

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Towards more standard
by Stefan Matthias Aust 31 Dec '98

31 Dec '98

Hi! When moving mySelf from VisualWorks to Squeak, I noticed three problems. Some of them could be easily fixed, some trigger greater changes. I'd like to discuss them. 1. VisualWorks (and other Smalltalk systems, too) accept '_' as valid character in selectors and quoted symbols. As Squeak uses '_' as assignment operator, it doesn't allow them in selectors. However Squeak also accepts ':=' as assignment operator and I wonder why Squeak still keeps with that old syntax. Okay, you may like the old syntax better, but IMHO the argument to stay compatible with current systems has more weight. I'd like to at least optionally switch to the new syntax. I've a patch which adds a flag to the scanner. If set to true, '_' are accepted inside identifers, that is inside selectors and quoted symbols. For compatibility, a single '_' is still taken as assignment operator. 2. Squeak doesn't allow to construct symbols from strings, using #'abc'. Adding this is one trivial change in the Scanner (xLitQuote) and another one in Symbol class>>intern: to support the now possible empty symbol #''. As this patch doesn't break any existing code, I'd really like to see this incorporated into the base system. I can also provide this patch file. 3. I like to use block-local temporary variables. Squeak doesn't support this. So I had to rewrite these methods. Actually no big deal, and the effort to add this kind of variables to the Parser is probably better spend on true closures which then would allow them anyway. However, it's something one has to think about when coding for more than one dialect. bye -- Stefan Matthias Aust // Are you ready to discover the twilight zone?

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Re: Float Question
by dick＠cfcl.com 31 Dec '98

31 Dec '98

>> 52 bits of significand. As I sit listening to Professor Kahan on tape while reading "52", I see on the other monitor the number 53. The larger number is actually the right one, despite the fact that 53+11+1 > 64, because, for normal numbers, the leading bit of the significand is boring. It is always on. That's what normalization does, after all. Since it is so boring, we need not even store it. Dick

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Re: Float Question
by Tim Olson 31 Dec '98

31 Dec '98

>"R. A. Harmon" <harmonra(a)webname.com> asks: >>> The ANSI proposed standard document talks about floating point object >>> representation containing denormalized values. I think I understand pretty >>> well floating point object representation conceptually, but what are >>> denormalized values? Does the Squeak implementation use them? [Bruce Cohen replies with a good description of normalized vs. denormalized representations]. Awhile back some of the Float stuff in Squeak got cleaned up a bit, and in that cleanup we made sure that Squeak dealt gracefully with IEEE-754 Infinities, NaNs, and denormalized numbers. >AFAIK, it's a straightforward IEEE 754 double-precision (64-bit) >representation. That's what the Float class comment implies; I haven't >looked at the primitive code to check that. IEEE has one sign bit, 8 >bits of exponent (with an offset of 127, so as to represent -126 to >+127, with 0x0 and 0xFF reserved for 0 (mantissa is ignored) and >underflow/overflow), and 23 bits of mantissa. Thats for IEEE-754 single-precision; Squeak uses the double-precision representation, which is 1 sign bit, 11 exponent bits (excess-2047), and 52 bits of significand. -- tim

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Announcing mySelf
by Stefan Matthias Aust 30 Dec '98

30 Dec '98

Hi! Out of curiosity, I wrote a simple Self parser and simulator which I've also ported to Squeak. The Squeak port is really crude right now, but perhaps somebody is already interested in the code. If you like, check out my web page at http://freeweb.digiweb.com/computers/sma/ MySelf isn't really useful right now, but it was (and still is) fun to play with :-) Now, there's a dream which might come true. I wonder whether it might possible to integrate mySelf into the Squeak VM, eventually creating a more complete (and/or hybrid) Self system based on Squeak. As I did the simulator in pure Smalltalk now, I've already some ideas for this. It shouldn't be that difficult. Anybody interested in this project? I'm not talking about implementing the sophisticated Self compiler (aka HotSpot) right now, but an interpreter which can (probably slowly) evaluate non-trivial examples - perhaps even morphic. Large parts of the Squeak VM can be reused for this, I think. We'd need of course a number of additional primitives, but otherwise, Self is even more simple that Squeak on byte code level. Happy New Year! bye -- Stefan Matthias Aust // Are you ready to discover the twilight zone?

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Re: Float Question
by Rick Zaccone 30 Dec '98

30 Dec '98

>So why use denormalized numbers at all? It costs time to normalize the >denormalized result of an operation; if you know the loss of precision >is not significant to your computation, you may not want to pay the >price, especially in an inner loop of a vector or matrix operation. >Also, you can get a few extra bits of exponent (read: dynamic range of >the value) in trade for the loss of mantissa precision. The primary reason for denormalized numbers is to provide gradual underflow. Denormalized numbers allow for some additional values between zero and the smallest normalized number greater than zero. Rick Zaccone -- zaccone(a)bucknell.edu

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[Q] Chaing Default Display Font in Squeak
by Ninja 30 Dec '98

30 Dec '98

I want to change default Squeak font NewYork(?) to Comic Plain. I like this font but I do not know where I can change this. Yes, I know per window by window using menu, but what I want to is changing all display font in my squeak. Thanks in advance.

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Float Question
by R. A. Harmon 30 Dec '98

30 Dec '98

The ANSI proposed standard document talks about floating point object representation containing denormalized values. I think I understand pretty well floating point object representation conceptually, but what are denormalized values? Does the Squeak implementation use them? I'm also curious about how Squeak represents floating point objects. I'd appreciate it if anyone could give me a quick explanation. -- Richard A. Harmon "The only good zombie is a dead zombie" harmonra(a)webname.com E. G. McCarthy

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