If you got as excited as me about Dan Ingalls' live Smalltalk-76 demo on an actual 1970's Xerox Alto, you may have wanted to try it yourself. This is actually possible, and here is how:
First, you need an emulator for the Alto computer. Ken Shiriff posted a nice piece on how to run ContrAlto on Windows. It is written in C# and I got it to work on my Mac using Mono. So here's a step-by-step:
Unzip both ContrAlto-mono.zip and xmsmall.zip in the same folder.
In a terminal, change to the ContrAlto directory and run mono Contralto.exe. This opens the Alto screen in a new window, and the emulator control in the terminal.
(if you get an error about a missing SDL library at this point, install that via homebrew using brew install sdl2)
At the emulator's ">" prompt, type load disk 0 xmsmall.dskand thenstart:
$ mono Contralto.exe
ContrAlto v1.2.2.0 (c) 2015-2017 Living Computers: Museum+Labs.
Bug reports to joshd@livingcomputers.org
You are at the ContrAlto console.Type 'show commands' to see
a list of possible commands, and hit Tab to see possible command completions.
>load disk 0 xmsmall.dsk
Drive 0 loaded.
>start
Alto started.
>
In the Alto screen window, type resume xmsmall.boot to start up Smalltalk-76:
And now you should see Smalltalk-76 running!
There is no explicit "save" option. The OOZE object swapping system continuously writes objects to the disk. Use "quit" from the main menu to flush all objects back to disk.
Note that you will need a 3 button mouse to properly interact with the system. On my MacBook, I installed MagicPrefs to emulate a third mouse button. After installing, in MagicPref's "MacBook Trackpad" section, for "Three Finger Click" choose "Middle Click".
You will also need some keyboard shortcuts to access the special characters in Smalltalk-76:
ctrl A ≤ (less or equal) ctrl B bold ctrl C user interrupt ctrl F ≡ (identical) ctrl G ◦ (index operator) ctrl I italic ctrl N ≠ (not equal) ctrl O ↪ (quote) ctrl Q ⇑ (return) ctrl R ≥ (greater or equal) ctrl S 's (eval operator) ctrl T ┗ (prompt) ctrl U ¬ (unary minus) ctrl X clear emphasis ctrl / ⇒ (if then) ctrl = ≡ (identical) ctrl shift = ≠ (not equal) ctrl \ ≠ (not equal) ctrl ] ⌾ (create point) ctrl [ ◦ (index operator) ctrl : ⦂ (open colon) ctrl ' ↪ (literal quote) ctrl < ≤ (less or equal) ctrl > ≥ (greater or equal) shift - ¬ (unary minus) cursor down doit (in dialog view)
Originally printed in Michael Swaine's PragPub. https://theprosegarden.com/
“man is much more than a tool builder … he is an inventor of universes.”
Alan Kay - “A Personal Computer for Children of All Ages”
There is a race between the extraordinary and compelling Augmented Realities – and the necessary and powerful Augmented Human. It is essential that these be in balance or we will become a slave to the increasingly virtual world we live in rather than the master of it. We consider here the idea of a truly Augmented Reality – a digital extension to the world in which we will live all our future waking hours. A far more important concept is that of the Augmented Human – our next steps in evolution that will allow us to understand and control this Augmented Reality and, in turn, the universe. The Augmented Human is a better you.
What is AR
I consider VR (virtual reality) to be a full subset of AR (augmented reality); a mode if you like. I deeply understand and appreciate the difference between the two, but I think that it is as irrelevant as trying to draw a line between smart phone and an MP3/music player.
I suppose I should give you my definition of what Augmented Reality will be. It is concise.
AR will be everything your smart phone is today, but it will be visible every waking second, displaying the world as a living web browser.
This last is important, as it subsumes everything else. Think about how you use the web on a daily, or sometimes even minute by minute basis. Why is this important? Because AR will be like that but so much more. It will be amazingly addictive, and as we all know, addicting products are by far the best market – just ask the cigarette manufacturers.
Imagine an interesting opportunity for distraction every step you take walking down a city street. I am not just talking about restaurant menus here. You can query a quaint hotel you are standing beside and view a list of the famous people that lived … and died there. Interesting that it was once a brothel, even more interesting how that movie star ended up in a closet. Who was the architect, what other buildings did he design? When did he die and what from? What was the Spanish Flu, anyway?
Everything you look at or is near you becomes a trigger for a wonderful exploration of streams of information and ideas. It will be useful in other ways too - you can look down through the pavement and see the subway lines and watch the trains move down the tracks. SimCity comes to life and you and everyone around you is a Sim. You can query for the closest subway stop, which cars are most crowded, are there any sexual predators on the car you are planning to get on? No problem, you have set your system to automatically tag people like that – when you do see him, he is painted a bright red and has a neon sign floating over his head. You can even select his history.
You walk past a car dealership and see a new sedan in the window. You pause to step into a fully immersive (VR) virtual car seat to explore its interior and try out a few features (without leaving the sidewalk). Oops, you are alerted that your red painted guy has just stepped within 100 feet of you.
Time to move on.
Walking through a crowd, you can see Facebook icons pop over the heads of everyone that is a friend of yours on that service. I am talking about what is technologically feasible, not necessarily what society will approve of, but who knows. You see a good-looking person walking your way – cool, you can see that they are only one degree of separation from you on LinkedIn. You invite them into your network.
One of the creatures from a game you are playing appears from behind a car. It sees you and tries to escape, but you corner and capture it.
You get an alert that your video conference is about to start. Walk into the nearest Starbucks – immediately pick up the coffee you already ordered and paid for and sit down at an empty table. The other participants soon join you. Your AR device captures the position of your head, your face and facial expressions and of course where you are looking. Your colleagues look almost as live as if they were sitting next to you. No one else in the coffee shop even notices or cares that you are in a conversation with ghosts. One of the conference participants drops a document onto the table. It is a 3D chart of the projected growth of the new IoT toaster. The new toaster has just integrated Alexa, so it can carry on a conversation with you along with the rest of your other kitchen appliances. You have never met one of your colleagues in person and are not aware that he has removed a mole from his virtual cheek and has a virtual nose job.
The hot new app allows you to transform any of your friends into Hollywood characters, including their voices. You have decided that one of your co-workers will be Humphry Bogart, including hat and trench coat. Your boss is Hannibal Lector from Silence of the Lambs – it makes everything he says so much more interesting. The receptionist becomes Rhett Butler – Clarke Gable with a sort of southern accent.
Most of these capabilities already exist in some form – probably on your phone. All of them will exist soon. They are just a bit inconvenient to access today. That is why you don’t use them every second. You can’t. Yet.
Friction
That sounds like a wonderful world. Why don’t we have it now? When can we have it?
Today, AR and VR are not great experiences. They are terrible. Current devices are complex, hard to set up, even harder to use. They are ugly, heavy and don’t really do much. They do sort of show what is possible once you finally get it working, but at the same time they highlight just how bad the current state of the art is. VR games demonstrate t he potential of the new medium, but even there, it is difficult to spend the same amount of time and attention that you would bring to a screen based version.
Friction is the barrier that your product must overcome to satisfy the customer.
In marketing, the reverse of Friction is, oddly enough, Stickiness. Today, a smart phone is incredibly sticky. AR and VR has a great deal of friction to overcome.
Compare AR and VR to the smart phone in your pocket. AR fails in so many ways.
Phones are beautiful, sleek, elegant – AR makes you look like an alien Bono with an umbilical cord. VR is worse, as not only can’t you see the world, the world sees you with a literal box on your head.
Phones are invitingly seductive and like to be touched. The user strokes their finger across the screen, creating wonderful ripples in their personal probability pond.Interestingly, phones are quite useless for fine manipulation. It is very hard to edit a document on the phone – almost impossible to select between letters in text. That fine manipulation is very important as we will see later. AR and VR have pointing rods with almost no haptic feedback at all aside from perhaps vibrating. It has none of the compelling qualities of the phone interface and is not even particularly good at gross manipulation. I know some people do amazing things in VR. Frankly, I am amazed that they can do that. I can’t. Picasso could draw amazing things in the air too. But he was Picasso.
We need a new way of interacting with this new idea space in the same way that the mouse was invented to be able to interact with our virtual desktop.
Phones are relatively inexpensive and self-contained. A great phone costs almost nothing, a high end one is still amazingly cheap for what you get.Consider the power it provides when you have it in your hand. You don’t need to plug anything into it or plug it into anything to use it. It is a complete and efficient distraction. AR and VR usually require a wire with a hefty, expensive computer on the other end. There are cheaper alternatives, but there is a significant gap in capabilities.
Phones have so many interesting things you can do with them. Communicating with your friends, watching videos, playing games. VR and AR are still emerging markets based up some very flawed hardware. Developers consider the size of the target market for their apps, and though the phone today boasts billions of users, the user base for VR and AR worlds is in the relatively inactive millions.
Phones are instantly available and invisible. Your phone is in your pocket or purse. It alerts you that it wants attention and you have it turned on and in front of your face in just a few seconds. Most people do not remember taking their phone out to use it. It just magically appears in their hands and takes over their focus. You never think about using the phone when you are using the phone – you see through it to the rich world on the other side of the screen. On the other hand, you have no choice but to think about AR and VR when you are attempting to use it from the time you set it up, to when you are engaged and immersed within it to when you try to do anything within it. It forces you to see the device as much as the world it is trying to present.
This last is very important. In a way, phones own you more than you own them. They constantly cry for your attention, and when they have it, they study you to determine how best to continue to keep you occupied. The phone is literally using the data it gets from you to figure out how to make itself even more addicting to you. Now that is a great drug.
If phones are such a powerful force that we can’t resist them or maybe even live without them, why does AR matter?
Because phones only OWN you. AR is everything a phone is but will BECOME you.
A Better You
AR has some serious challenges but not one of them is insurmountable. What would AR devices be like for it to offer a serious challenge to the phone?
Most of all, AR must be friction free. It must be and will be easier to use than a phone. You just put it on your head and leave it there – a lightweight pair of glasses that look just like those you might be wearing today. You no longer search all your pockets to find it and then swipe your fingerprint or enter a code or stare deep into the eyes of the phone – the camera – hoping you look somehow like you did when you got to know it. AR knows when you want it. It hears you when you speak. It knows what you are looking at. So be good for goodness sake. It will seem like you just think something, and it immediately appears. That is an invisible interface. Your phone is a boat anchor compared to AR done right.
AR must do everything a phone does now. AR devices will be phones – or at least a seamless extension of them. In turn, Will Wright pointed out that technology is an extension of the human body. If somebody hits your car, you don’t say that “my car was hit”. You say “someone hit me while I was driving”’. The car becomes “me”, an extension of your body. Your phone is an extension and a reflection of you in the same way, but AR is far more intimate and compelling. It is you.
AR must look cool. Or it must be worn by someone that is cool so that you think it is OK to wear it too. We are so shallow. It also needs to be lightweight, as well as cool (as in temperature).
noun: synergism
1.the interaction or cooperation of two or more organizations, substances, or other agents to produce a combined effect greater than the sum of their separate effects.
When AR is really great, and it will be, you are going to put on your AR device in the morning and wear it all day long. It will be like hearing aids or dentures – or glasses. Indeed, normal glasses (and in-the-eye glasses from cataract surgery) augment your vision so that you can see the real world. Without them, you are blind, if not totally, to a debilitating degree. The same thing is true of a light bulb in a closed room. Nothing is visible until you turn the light on. As McLuhan says: “a light bulb creates an environment by its mere presence”. Does the room exist without the bulb? Yes, but you could not see it, and would have a great deal of trouble interacting with it. But you never think about technologies like a light switch – they are friction free and have disappeared in a sense, though indeed they redefined what you are at a fundamental level. The digital world already exists – and is as much a part of our existence as the physical, but we are quite blind to it. We see glimpses of it in our offices and labs every once in a while, (at least I get to), and there is no question that the virtual light will soon be turned on. And just like with our glasses and light bulbs, the medium will seem to disappear, but in fact will redefine what we are.
This thing is far stickier than a phone. It is going to be the fusion of man and the Internet. The line between the two is about to be erased. And it is going to be glorious – and terrible.
The Bus or the Bulldozer
Though it is rare that you use a computer to think, you never use a phone that way. You are a consumer of information, not a creator. Part of this is due to the phone’s limitations. You simply can’t be truly creative as a human today without fine manipulation. The phone interface is designed around gross manipulation because touch screens don’t allow you to easily specify a touch point – it is a touch area. This means the interaction targets on the phone must be larger to accommodate the gross manipulation that you can do with it. Without fine manipulation, it is very difficult to create, but virtually impossible to edit anything interesting. The vast majority of effort in creating anything interesting is in the editing, re-working, re-thinking. Things that you just can’t do with a phone. This doesn’t mean it is impossible – we are often impressed by some beautiful work that was created completely on a phone. Impressed not just because the creative effort is better – but because it could be created and completed that way at all.
That limitation in creativity is partially due to the inherent limitations of the design of the smart phone. It has a small screen and you have big fingers. But the display itself is small, which means that you don’t really have the room to express yourself if you wanted to. Real artists need room.
What is quite interesting is that this limitation became something of a feature – as far as the phone manufacturers saw it. The phone is not a very good creative device. However, it is an amazing consumer device. Consuming has two parts. Select what to consume – then consume it. We don’t need a particularly fine interface for that. More problematical was Apple Computer’s decision to enshrine this “feature” and to not allow any kind of programming environment on their phones at all. In fact, Scratch – a block programming language designed for children that works great on a phone – was blocked from the app store for many years until recently. This was an attempt to enforce the consumer nature of the device and it succeeded.
Phones are designed around the idea that you are a consumer of information and ideas. You can control where you go, but you can’t go anywhere that the phone hasn’t already anticipated. This is like getting on a bus. If you already know where you want to go, this is a convenient and fast way to travel there.
However, you can’t take the bus to someplace that is new and unexplored. For that, you need a more refined and powerful set of tools. You are better off with a bulldozer, something that is responsive to new ideas and lets you go anywhere you want. There are no barriers, except your imagination.
That is the true promise of AR – assuming it can escape the challenge of gross manipulation versus fine manipulation.
Amplifiers
Why is it necessary to use AR and VR as creative platforms? How do we ensure that the human is empowered to extend, explore and share their ideas and their worlds? How do we amplify the properties that define humans as creative tool builders?
First, we can’t really understand how AR should work until we can create and modify the AR system from within it. It must be a creative amplifier. Our creations extend the capabilities of the system which then allows us to create something even better. The problem of AR today is that it is being built from the outside – like a ship in a bottle, with the intent that it can then be launched and won’t sink. It might be beautiful indeed, but you are coming at it from the wrong direction. Instead, we need to launch a raft with just enough capabilities so that we can design a ship as we learn to navigate the ocean. We will design the right kind of ship because it is the one we will be living on. We need to invent the VR and AR interfaces from within it and as we use it. This is not a new idea – it was the foundation of what Doug Engelbart demonstrated 50 years ago, create tools that allow you to create even better tools. Xerox Parc created the modern UI for computers and phones from within Smalltalk. Smalltalk allows the developer to reinvent every aspect of the system, from the foundational operating environment underneath to the actual widgets that the user can manipulate. Almost everything you use on a modern computer or phone was invented at Xerox in this way. I believe it is the only way to create a truly new and powerful platform. Will Wright describes it this way:
“We now, with these little micro-worlds, have the ability to basically externalize what is in our imagination and share it with other people. You know, it used to be that you had to have a very rich skill set, like you had to be a fine artist to do that – you know, to paint something in your imagination and then share it with other people. But now with these tools, the creative leverage they give us, average, casual game players have the ability to externalize, create things out of their imagination, share it with other players, and actually have these shared imaginary worlds. And so I think that’s one of the examples of the computer giving creative leverage – a creative amplifier.”
Second, we need a vehicle to amplify our intelligence, both individually and collectively. Humanity is in a race with itself to determine its fate. We may be losing this race. We need to provide the right side with an unfair advantage that it very seriously lacks today. We may not be able to get there from here, at least not directly. Doug Engelbart demonstrated a new starting line in this race 50 years ago. He not only showed many of the foundations of human computer interface that we now take for granted, he also provided us with a new perspective on what the computer could really mean as an extension of a human. This was not an accident, but a pre-planned intentional act to redefine the nature of how the computer and human engage to become something greater than their parts. A synergism that defines the symbiont.
Even more spectacular was how he harnessed the newly empowered symbiont to include other humans, equally empowered with these technologies, so that they could collaborate to explore and create even greater things. His goal wasn’t to merely amplify the intelligence of a human – he intended to amplify the intelligence of humanity. For AR to truly shine, we must also look at it as a fundamentally disruptive event. AR isn’t a better phone, though the first popular versions of it will likely embrace that approach. They will be the first demonstration of what Augmented Reality has in store for us – for better and worse. We need something far more powerful – a tool that allows us to think,explore, and create new tools that amplify our intelligence even more. Engelbart’s tricycle is a great analogy to the problem. Extending the phone into AR, with its inherent limitations and biases is like improving the capabilities of a tricycle. The new tricycle will be based on user feedback and will be a very compelling product, very stable and safe. It offers an awesome user experience, and is what everyone thinks they want. But that process will never result in a bicycle, a far more powerful product that dramatically multiplies its users speed. This is a disruptive product and requires what Clayton Christensen referred to as “discontinuous” innovation. Apple used to refer to the Macintosh as a Bicycle for the Mind – and indeed the Macintosh provided many of us with an incredible vehicle to construct new realities with. The Mac was NOT a better Apple ][. It was a very new thing. Our challenge is to ensure AR is done right.
Third, we need an intention amplifier. We need a new approach to user interaction in the 3D world that provides us with the free-form gross gestures that we have, but also the fine control that we get with the mouse, another Engelbart invention. The mouse was not an accidental design –Engelbart explored many alternatives for interfacing with the computer. The mouse was significantly better. The mouse amplifies the user’s actions while retaining control. Even on a large, multi-foot display like the one I am using, I can move my mouse from one side of the screen to the other and still be able to place the cursor between two letters to edit this document. The mouse amplified my reach but maintained the necessary fine control.
We have far better sensors than Engelbart had in his day. An equivalent to the mouse is certainly within reach. The body and hand are obvious targets for enhancement, but it is a mistake to simply project the bodies motion into the 3D world. Great user interfaces are invisible. The user thinks about what they want and the necessary actions to accomplish it occur. You don’t think about using a mouse – you think about what you want to be true. The best interfaces for AR will be based upon eye-tracking and voice. Hands, finger motions and gestures will aid that interface in the way meta keys aid the keyboardist, but these will be exceptions.
Fourth, we need a control amplifier. Facebook and Google make money by aggregating large amounts of attention and selling it to the highest bidder. Further, they train, or allow others to train the users to desire certain things. The main goals of machine learning on these platforms is to understand what people want and to then provide it to them. We see an almost real-time morph into these machine learning systems exploiting a user’s weakness to train them in what they might desire. Manipulating human behavior is a game, and Machine Learning systems are extremely good at games. The alternative is that the machine learning systems be harnessed to enable the individual user’s creativity and exploration. It should be a full partner in engaging, constructing and exploring new virtual universes. It needs to become another vehicle for fine manipulation by the user, an even sharper blade for our bulldozer enabling us to drive anywhere we want.
We are in a race between the extraordinary, compelling and addicting augmented realities – and the necessary and powerful augmented human. It is essential that these be in balance or humanity will become a slave to the increasingly virtual world we live in rather than the master of it. Augmented Reality is the place where we will live all our future waking hours. The “real” world as we know it will still be the digital world will co-exist and be mixed-in with it and be just as relevant as a light switch in a dark room is today. The digital world exists – you just can’t see it yet. The Augmented Human is our next step in evolution. We will understand, control, and extend this augmented reality and, in turn, the universe. We are about to turn on the light.
by David A. Smith (noreply@blogger.com) at January 15, 2019 03:22 AM
I just posted the video I made of Virtus Walkthrough. I created this in 1990 with David Easter and Mark Uland. I am actually demonstrating Virtus 4 here. Scott Haynes was responsible for this version, and I think it is the best version of Walkthrough we ever did. It was also, unfortunately the last. The overall design and interaction is almost identical to the original 1990 version, though. This is using a software renderer that I wrote and was greatly enhanced by the team led by Greg Rivera. It uses portals extensively, and though you won't notice it, it does not actually have a z-buffer. The objects are sorted using a kind of BSP thing I did that is extremely fast. I am actually running this on Parallels on an older Macbook, and it feels faster to me than Sketchup 7.1, which I run native. But of course, considering that this had to run in real time on sub-20 mHz 68010 and 68020 machines, this had to be pretty damn fast to work at all.
This is the system I first prototyped the virtual collaboration space in that I showed to Alan Kay. This led to the development of ICE (see previous post), OpenSpace, the Croquet Project, and Teleplace.
Virtus Walkthrough won many awards, including the very first Breakthrough Product of the Year from MacUser Magazine, and the PC Computing Best Drawing Program, where we beat Adobe Photoshop.
Here is the demo:
https://www.youtube.com/watch?v=RKYMZzGPSjM
by David A. Smith (noreply@blogger.com) at September 01, 2018 03:10 AM
In this post I want to share the details about the latest project being done on Krestianstvo SDK. Virtual World Framework provides a robust decentralised architecture for building virtual world apps based on replicated computation model. It's JavaScript version is strongly based on ThreeJS ibrary for programming apps with 3D visualisation and deep interaction support. So, for building such apps, the developer should be aware of ThreeJS internals, not to mention the knowing of the VWF component's architecture. But, actually VWF is working just with any programmable elements whatever simple they are. The A-Frame framework solves the problem of ThreeJS сomplexity for developing Web apps for Virtual Reality. It provides the component-based architecture for that. A-Frame incapsulates ThreeJS, hiding the internals, and providing high-level interface for describing web app declaratively. So, I have developed a model and view drivers for VWF, that provides basic support for using A-Frame components in Virtual World Framework apps. That allows to build a VWF collaborative apps with 3D visualisation, WebVR, HMD, trackers and mobile devices support easily.
Here is a small video demonstration, that shows the interaction within collaborative Virtual World Framework app, which is composed by the A-Frame components.
In the video three Google Chrome web-browsers are directing to the same VWF app instance's URL. Every browser shows the replicated A-Frame scene with components in it. The users are represented with small cubes and are visible to each other. The cube on the right is holding the simulation, which is staying the same on all browsers.
While working on my SqueakJS VM, it became necessary to deconstruct floating point numbers into their mantissa and exponent parts, and assembling them again. Peeking into the C sources of the regular VM, I saw they use the frexp()and ldexp() functions found in the standard C math library.
Unfortunately, JavaScript does not provide these two functions. But surely there must have been someone who needed these before me, right? Sure enough, a Google search came up with a few implementations. However, an hour later I was convinced none of them actually are fully equivalent to the C functions. They were imprecise, that is, deconstructing a float using frexp() and reconstructing it withldexp() did not result in the original value. But that is the basic use case: for all float values, if
[mantissa, exponent] = frexp(value)
then
value = ldexp(mantissa, exponent)
even if the value is subnormal. None of the implementations (even the complex ones) really worked.
I had to implement it myself, and here is my implementation (also as JSFiddle):
function frexp(value) { if (value === 0) return [value, 0]; var data = new DataView(new ArrayBuffer(8)); data.setFloat64(0, value); var bits = (data.getUint32(0) >>> 20) & 0x7FF; if (bits === 0) { // denormal data.setFloat64(0, value * Math.pow(2, 64)); // exp + 64 bits = ((data.getUint32(0) >>> 20) & 0x7FF) - 64; } var exponent = bits - 1022; var mantissa = ldexp(value, -exponent); return [mantissa, exponent]; }
function ldexp(mantissa, exponent) { var steps = Math.min(3, Math.ceil(Math.abs(exponent) / 1023)); var result = mantissa; for (var i = 0; i < steps; i++) result *= Math.pow(2, Math.floor((exponent + i) / steps)); return result; }
My frexp() uses a DataView to extract the exponent bits of the IEEE-754 float representation. If those bits are 0 then it is a subnormal. In that case I normalize it by multiplying with 264, getting the bits again, and subtracting 64. After applying the bias, the exponent is ready, and used to get the mantissa by canceling out the exponent from the original value.
My ldexp() is pretty straight-forward, except it needs to be able to multiply by very large and very small numbers. The smallest positive float is 0.5-1073, and to get its mantissa we need to to multiply with 21073. That is larger then the largest float 21023. By multiplying in steps we can deal with that. Three steps are needed for e.g. ldexp(5e-324, 1023+1074) which otherwise would result in Infinity.
So there you have it. Hope it's useful to someone.
Correction: The code I originally posted here for ldexp() still had a bug, it did not test for too small exponents. I fixed it above, and updated the JSFiddle, too. Also, Nicolas Cellier noticed other rounding and underflow problems, his suggestions for ldexp() are now used above.
by Bert (noreply@blogger.com) at November 03, 2016 06:16 PM
TL;DR: Try Etoys in your web browser without a plugin (still buggy, but even works on iPad). Feedback from more platforms is very welcome, and fixes to improve the compatibility, too.
—
Half a year has passed since my initial release of SqueakJS. Now I can report on some significant progress since then.
For one, I adopted a UI layout similar to Dan’s Smalltalk-72 emulator, where the debugger interface is only visible when the system is stopped. Now that the basics are working, there is no need to show the debugger all the time. Try it yourself at the Lively page.
But more importantly, many more subsystems are working now. BitBlt is almost complete (all the important modes are implemented), WarpBlt works (for scaling and rotating morphs), the image can be saved, an emulated file system supports reading and writing of persistent files. This now is enough to not only run the very old and undemanding “mini.image”, but SqueakJS now can even run the very latest Etoys image, the same version as on Squeakland. Beware of the many incomplete features and outright bugs still left to be fixed, but try it for yourself here.
While Etoys feels a lot slower than the MVC “mini.image”, and some operations take many seconds, it is surprisingly responsive for normal interaction. On the browsers with the fastest JIT compilers (Safari on Mac, IE on Windows) it is almost good enough, even though no serious optimizations were done yet. It is also interesting to see that some browsers (Chrome and Firefox) are currently significantly slower. And not just a little slower, but Safari outperforms Chrome by 200% for this workload! This is likely due to Safari›’s excellent LLVM-based FTL JIT.
The remarkable thing about the screenshot above is how unremarkable it looks. Apart from the missing white oval behind the “Home” label it looks just like it’s supposed to. In comparison, a week ago the screen still looked like this:
The difference is that Tobias Pape and I added support for Balloon2D rendering. This is Squeak’s default vector rendering engine, originally created by Andreas Raab to show Flash animations. But unlike the rest of the SqueakJS VM, we did not port the original code. Instead, our plugin intercepts the drawing commands and renders them using HTML5 canvas drawing routines. While still far from complete, it can already render one kind of important shapes: TrueType font glyphs. They are defined by Bézier curves, which need to be rendered with anti-aliasing to look nice. And now that we can render text, the graphics are almost complete. Many more details still need to be implemented, especially color gradients.
This highlights one strength of Squeak: The VM and its plugin modules present a well-defined, stable interface to the outside world. That is what makes a machine truly “virtual”. In contrast, other systems rely on FFI (the foreign function interface) or similar techniques for extension. While convenient during rapid development, it does not keep the interface small and stable. That interface is overly broad and unpredictable. Typically, client code must be special-cased per platform. It's calling C functions directly, which may or may not exist on a given platform. That makes it much harder to move the system to another platform, and in particular one that is completely different, like the web browser. The Squeak Etoys image on the other hand did not have to be modified at all.
What I’d like to see fixed in Squeak is that there should be working fallback code for all non-essential primitive functions. This would make it much easier to get up and running on new platforms.
For SqueakJS, bugs need to get fixed, and many features are still missing to run Etoys fully. Adding support for other Squeak releases than Etoys would be great (closure/Cog/Spur images). Contributions are welcome: fork my github project.
by Bert (noreply@blogger.com) at July 04, 2014 08:42 PM
It was inspired by Dan's JSqueak/Potato VM for Java, and similarly only runs the old Squeak 2.2 mini.image for now. But I developed it inside the Lively Kernel, which allowed me to make a nice UI to look inside the VM (in addition to all the Lively tools):
It represents regular Squeak objects as Javascript objects with direct object references. SmallIntegers are represented as Javascript numbers, there is no need for tagging. Instance variables and indexable fields are held in a single array named "pointers". Word and byte binary objects store their data in arrays named "bytes" or "words". CompiledMethod instances have both "pointers" and "bytes". Float instances are not stored as two words as in Squeak, but have a single "float" property that stores the actual number (and the words are generated on-the-fly when needed).
For garbage collection, I came up with a hybrid scheme: the bulk of the work is delegated to the Javascript garbage collector. Only in relatively rare circumstances is a "manual" garbage collection needed. This hybrid GC is a semi-space GC with an old space and a new space. Old space is a linked list of objects, but newly allocated objects are not added to the list, yet. Therefore, unreferenced new objects will be automatically garbage-collected by Javascript. This is like Squeak's incremental GC, which only looks at objects in new space. The full GC is a regular mark-and-sweep: it's marking all reachable objects (old and new), then unmarked old objects get removed (a very cheap operation in a linked list), and new objects (identified by their missing link) are added to the old-space list. One nice feature of this scheme is that its implementation does not need weak references, which Javascript currently does not support.
This scheme also trivially supports object enumeration (Squeak's nextObject/nextInstance primitives): If the object is old, the next object is just the next link in the list. Otherwise, if there are new objects (newSpaceCount > 0) a GC is performed, which creates the next object link. But if newSpaceCount is 0, then this was the last object, and we're done.
The UI for now copies the Squeak display bitmap pixel-by-pixel to a typed array and shows it on the HTML 2D canvas using putImageData(). Clipboard copying injects a synthetic CMD-C keyboard event into the VM, then runs the interpreter until it has executed the clipboard primitive in response, then answers that string. This is because the web browser only allows clipboard access inside the copy/paste event handlers. You can drag an image file from your disk into the browser window to load it.
Besides running it on your desktop, you can install it as offline web app on an iPad:
On the iPad there is neither right-click nor command keys, but the menu is available on the inside of the flop-out scrollbars. It needs a fairly recent browser, too - it works in iOS 7, but apparently not in older ones. On Android it works in Chrome 31, but not quite as well (for example, the onscreen-keyboard does not come up on an Galaxy Note tablet).
Go to the project page to try it yourself. The sources are on GitHub, and contributions are very welcome.
Have a great Christmas!
by Bert (noreply@blogger.com) at July 04, 2014 03:47 PM
I am very excited with the ADL Sandbox project and Virtual World Framework at all, and that it is available in open source to experiment with. By the way, I am from Smalltalk world and an acceptor of OpenCroquet architecture, which has it's own history. OpenCroquet in it's latest form of OpenQwaq take all the features and benefits from the platform being realized on (the open source Smalltalk language dialect Squeak). But, Virtual World Framework goes further now, especially in moving from class based language architecture to prototypes, that gives a shared code and behaviours used in distributed computation, to be modified at runtime! So, that's one of the main criteria, I am start moving now from OpenCroquet to Virtual World Framework, despite of sadness of parting with all the benefits of Smalltalk language and it's IDE, comparable to JavaScript and Ruby. Although, I have the insights of looking a Smalltalk language as a DSL language for Virtual World Framework in the future (for example as Seaside web framework for HTML and JavaScript). ADL Sandbox project uses already one JavaScript language for all stuff. And one interesting thing to realize in it is having OMeta'JS workspace inside Sandbox script editor, which will allow to define own language's grammar and replicate it through the application instances, then have a running scripts on that shared grammar. Almost all JavaScript language dynamic capabilities will be used in distributed computation then. For example, you could have all the languages down from Logo (Turtle graphics) to Smalltalk available for scripting the virtual world just in the Web browser. More over the integration between LivelyKernel and Virtual World Framework will give the endless capabilities of in browser project development and editing. So, I have started using the ADL Sandbox project and Virtual World Framework to build a Virtual Learning Environment for modern mathematics and phisics, exploring the new ways of developing the concrete tools for modelling, rendering and interaction with the content of the virtual world. Will post about the progress here.
by Suslov Nikolay (noreply@blogger.com) at October 09, 2013 02:02 PM
Want to introduce the Curved Space Explorer for Squeak project, known as CCSE by Krestianstvo SDK. It is a Smalltalk port version of Curved Spaces, originally developed by Jeff Weeks (geometrygames.org) in C language. This Squeak version is derived from Krestianstvo SDK project's version, where Curved Space Explorer is collaborative in it's nature and available mainly for distributed computation. The aim of this project is to make Curved Space Explorer in Smalltalk being available for the large Smalltalk audience and mainstream Squeak distribution, so that anybody interested could work with it. The project is Open Source and the code is available here: http://sdk.krestianstvo.org/sdk/ccse.html
In running application there are some options available using the keyboard and mouse:
"up" and "down" arrows on the keyboard - speed of the ship movement "left" and "right" arrows on the keyboard - change aperture
mouse move with left button pressed - rotation of the ship mouse move with left button pressed and shift pressed - translation of the ship
press "o" on keyboard - switch between "head" and "body" rotation press "p" on keyboard - switching on stereo (anaglyph) mode press "l" on keyboard - switching shaders support (only for Mac OS X for now)
I have successfully proceeded in running TweakCore on the recent Squeak 4.4 trunk image (from Jenkins). And one of the famous existed applications developed in Tweak is the OpenGL procedural textures generator by David Faught. I make it also loadable to the current Squeak.
After playing with Flapjax library in Javascript, I moved to Reactive to
learn more about FRP. Because research on Functional Reactive
Programming is most active in Haskell, I thought it would be better to
do that. Reactive seems to be a nice library, but unfortunately I
couldn't find many working code examples. So I show some of them as my
exercise. To write this, I owe a maoe's great
article in Japanese.
As I didn't have much time, I couldn't write a good explanation
now. But still I hope it helps some people who learn Reactive like
me. I used Haskell Platform 2010 (slightly old) and did cabal install reactive --enable-documentation to install Reactive.
The first example shows "Hello, World!" after three
seconds. atTime generates a timer event, and <$>
convert this event to IO action (\_ -> putStrLn "Hello, World!") which
writes a string.
This is as same as above, but it makes events each second.
This makes running Fibonnaci numbers. You can use scanlE
to process previous value and current value of the event in a
function. In this case, (0, 1) is the initial value, and when
an event occurs, the function \(n0, n1) _ -> (n1, n0 + n1) calculates
next value, and the result (the first case is (1, 1)) is used as a
next argument when a new event occurs.
It shows characters as you type. It looks difficult but you don't
have to worry about run function. The important part is
machine :: Event Char -> Event (IO ()) that convert a
character input event to an IO action.
This example shows how to merge two events. onType is same
as machine in the previous example, and onClock is
same as helloMany.hs example. I used `mappend` to
merge the two events
This shows a simple state machine. The function next
defines the state machine, and mealy_ convert the definition
to an event. zipE is another way to merge two events. Unlike
mappend, you can see two values in the two events in a same
time.
by Takashi (noreply@blogger.com) at April 13, 2013 01:43 AM
The Raspberry Pi is a cute little computer. Quite cheap at $35, you plug in USB keyboard+mouse and a TV as monitor. And it is surprisingly capable, even for running 3D games.
One particularly interesting game is Minecraft: Pi Edition. As in other Minecraft versions, the main goal is to create a world. But unlike other versions, you can not only use the tools provided by the game, you can make your own tools! That's because it comes with a programming interface.
The Minecaft world is made of little cubes, and you normally place or remove these blocks by hand, one after another. This is fun, but for larger structures also quite cumbersome. For example, this rainbow here might take a long time to construct manually:
But I did not make the rainbow by hand. I programmed it, using the Smalltalk programming language. It's just these dozen lines of code in the Squeak programming environment:
Squeak is already installed on the Raspberry Pi, because Scratch was made in Squeak. Of course you need a little more to make this dozen lines of code work. Mojang (the developers of Minecraft) have provided "bindings" for the Python and Java programming languages, but not for Smalltalk. So I had to make these bindings first.
Here are the Bindings
Now you can use the bindings too, because I am publishing my code:
Squeak can either run on the Raspberry Pi itself (a VM is already installed) or on another computer in your network.
There are two packages, 'Minecraft-Pi-Base' and 'Minecraft-Pi-Demo', load them in this order. At the time of writing, the demo package has only the rainbow method in it. The code is not heavily commented, but from the examples it should be fairly obvious how to use it. The bindings are still somewhat basic, but cover all the functions of the current Minecraft-Pi 0.1.1 release. There is certainly room for improvement. E.g. it would be nice to add symbolic block names, so you could write "wool" instead of "35". And the hit testing (when you right-click on a block with your sword) works, but could be made more convenient to use, perhaps by introducing an event class like in the other bindings.
I made the repository open, so anyone can easily contribute. I'm curious what others will come up with. Like, control Minecraft from Etoys or Scratch? How about a Croquet bridge? Build a little game? In any case, have fun! :)
by Bert (noreply@blogger.com) at February 25, 2013 11:42 AM
Andreas loved to challenge me to express and exceed my abilities. In so doing, he forced me to challenge him. We pushed each other up the tallest mountains where, together, we had the honor of viewing the world from a new point of view.
He loved to program. He was the best programmer I have ever known – by a lot. This is not an idle statement – I have known and worked with the best in the world. Andreas was better.
He loved exploring and understanding new systems. He was fearless. He would not only understand how to use the new tool to accomplish his task, he would also figure out how to make it even better for the next person.
Andreas loved to make great things for people to use. He was never content with “good enough”. Every line of code he wrote was an opportunity to teach someone a new idea. Every system he built greatly empowered the person willing to embrace it and it allowed them a new freedom to create and explore.
He loved beer and introduced me to some fantastic brews. Learning to drink from a German is a valuable skill.
He loved to violently explore ideas. We had many loud discussions –often at a bar, where we threw ideas back and forth like rag dolls. Most ideas did not survive. The ones that did were very strong. He was as intent a listener as he was a proponent, and often succeeded in convincing himself he was wrong. He certainly convinced me he was right more often than not.
He loved food and was as essential a partner in exploring great restaurants as he was in exploring ideas. We visited Canto do Brasil in San Francisco every weekend we could and always had two (three?) Caiparinhas each and the Feijoada. And of course, the steak at Angus Barn… (yes, he was jealous when we went without him).
He loved language – he was always searching for how to express an idea in English with just the right word or phrase. He loved coding in the same way. He loved exploring the subtleties and power of how ideas could be expressed, communicated and unleashed.
Andreas loved classical music. We carpooled to work every day and he always had the radio on the classical station when he picked me up. We challenged each other on what the piece was, who the composer was, and even who the performers were. It was probably the only thing I was better at than him.
Andreas loved his friends. There were no conditions or requirements. He worked to see the world from their perspective – honoring them by always caring enough to understand them. He also expected them to live up to his high standards of thought, action, caring and love.
Andreas loved Kathleen. He was always a positive person, but he glowed from the moment he met her. He loved her more than anything else in his life. She completed his world and he completed hers.
by David A. Smith (noreply@blogger.com) at January 17, 2013 12:26 AM
SJ brought a hand-assembled XO-3 prototype to the OLPC Community Summit in San Francisco (mass production only starts when someone puts in a large-scale order), and of course I tried to run Etoys on it. It's pre-installed (as on all XOs) and worked right out of the box.
I was able to paint and drag objects, but since there is no right-click support yet there was no halo to bring up a new viewer. Also, touch targets are rather small for my adult-sized hands, and since there are no hover events, some features don't work correctly (as we found out with the iPad version two years ago).
So more work is needed, as well as for the XO-4 which has a multitouch screen in addition to a keyboard and touchpad. Help welcome :)
by Bert (noreply@blogger.com) at December 17, 2012 11:49 AM
"The Virtual World Framework (VWF) is a fast, light-weight, web-based architecture for creating and distributing secure, scalable, component-based, and collaborative virtual spaces. It leverages existing web-based standards, infrastructure, and emerging technologies with the intent of establishing a powerful yet simple to use platform that is built on top of the next generation of web browsers. " from http://virtualworldframework.com/
Here is the information about VWF, that is available on Internet for now:
Functional Reactive Programming (FRP) is a framework to deal with
time-varying data in a clean way. It is a combination of beauty of
functional programming and dynamics of object oriented
programming. The basic principle is easy enough as spreadsheets,
however, its vague scope and arcane terminologies keep you from
grasping it. It's not quite easy to answer the question such as what
makes FRP different from Observer Pattern, Data Flow, etc ??. I think
a good way to explain FRP is to compare FRP library against non-FRP
library, and I could show you where FRP is special, and pros-and-cons
of FRP.
I examined Flapjax as an example of FRP, and took Bred Victor's
Tangle as the comparison target. Although Tangle has similar goal of
FRP as he wrote "Tangle is a library for creating reactive documents",
its implementation is quite different from Flapjax.
Flapjax
Side-effect is hidden inside the framework. Time-varying data is
represented by dependent tree, and you can compose those trees to
implement a complex behavior.
Tangle
Tangle provides a simple framework and UI widgets, but the data
flow is represented by a normal imperative programming and
assignments.
Because of those properties, I think comparing the two libraries is
helpful to understand what FRP is. I hope it makes clear idea about
FRP in your mind.
Simple Calorie Calculator in Tangle
This is the first example from the Tangle's documentation. You can
modify the number of cookies by dragging, and it keeps calculating the
calories as you change the value.
When you eat cookies,
you will consume calories.
To make this nice reactive document. This document consists with two parts,
HTML for the view and javascript for the model.
<p id="tangle"
When you eat <span data-var="cookies" class="TKAdjustableNumber" data-min="2" data-max="100"> cookies</span>,
you will consume <span data-var="calories"></span> calories.
</p>
The HTML part is straightforward, this is just a normal HTML except
special attributes for Tangle. Data-var is used to connect
HTML elements to Tangle object's
properties. Class name TKAdjustableNumber makes a draggable input
control. Data-min and data-max are its
parameters.
var element = document.getElementById("tangle");
new Tangle(element, {
initialize: function () {
this.cookies = 4;
},
update: function () {
this.calories = this.cookies * 50;
}
});
The actual model of the document is described in the second argument
of Tangle object's constructor (new Tangle). It consists with
just two parts. initialize sets up the initial state,
and update is invoked whenever you modify the input value.
Tangle connects the model and the HTML element specified
by getElementById("tangle").
This initialize-update structure is fairly common among end-user
programming language like Processing and Arduino.
Simple Calorie Calculator in Flapjax
Let's move on to Flapjax. Unfortunately, Flapjax doesn't have a
nice input widget as Tangle has. Instead, we use a traditional input
field. But other than that, the behavior is identical.
When you eat cookies,
you will consume calories.
As Tangle, the Flapjax version has HTML part and Javascript
part. Note that Flapjax provides "Flapjax Syntax" which allows you to
write a simpler notation, but we don't use it because I want to
compare those as Javascript libraries.
<p id="flapjax" class="example">
When you eat <input id="cookies" value="4" /> cookies,
you will consume <span id="calories"></span> calories.
</p>
Flapjax's HTML part is similar as Tangle's. The element identifiers
(cookies and calories) are given by
id attributes. Unlike Tangle, the initial number of cookies is written
in the input field.
var behavior = extractValueB("cookies");
var colories = behavior.liftB(function (n) { return n * 50; });
insertDomB(colories, "calories");
In Flapjax, time-varying data is called behavior. The goal
of the program is to make a behavior which always calculates calories
of the cookies. It's not so difficult than it
seems. ExtractValueB creates a behavior from a form element,
in this case, extractvalueB("cookies") tracks every changes
happening in the input field named "cookies". This created
behavior is processed by the function at the argument
of liftB, in this case, whenever you modify
"cookies" field, colories represents a value which
is always 50 times by the number of cookies.
Eventually, insertDomB insert the content
of colories where HTML element
"calories" is and the calories are shown on the
screen. This element is automatically updated.
Unlike Tangle, there is no side-effect in the program. One
advantage of FRP is that you are not confused between old values and
new values. In Tangle's example, this.cookies is old value
(input) and this.calories is new value (output). But you are
free to be mixed up those. In Flapjax, a new value is always the
return value of a function, and there is no chance to be mistaken.
Implement Adjustable Number Widget in Flapjax
One of advantages of FRP is its composability. You can make a
complicated behavior by combining simple behaviors (occasionally,
imperative programming gives you a hard time for debugging if the bug
involves with connected program modules with side-effects). To
demonstrate this feature, I will show you how to make a Tangle-style
draggable widget in Flapjax. This problem is particularly interesting
because processing drag and drop involves a state machine, but a state
machine is not quite fit with a functional programming style. So you
might find pros and cons of FRP clearly from this example.
When you eat cookies,
you will consume calories.
The HTML part is almost identical except adjustable class in
the input field which points a Tangle like (but not fashionable
enough) stylesheet.
<p id="flapjax-drag" class="example">
When you eat <input id="cookies-drag" value="4" class="adjustable"/> cookies,
you will consume <span id="calories-drag"></span> calories.
</p>
The main Javascript part is also similar as above. But in this
time, we are implementing makeAdjustableNumber to make a draggable
widget from the element named "cookies-drag".
var element = document.getElementById("cookies-drag");
var behavior = makeAdjustableNumber(element);
var colories = behavior.liftB(function (n) { return n * 50; });
insertDomB(colories, "calories-drag");
A drag gesture consists of three events, mousedown, mousemove, and
mouseup. After a mousedown is detected, it has to track mousemove
events to know how far you are dragging. You can make such a state
machine to construct a higher order event stream. Here are two
new concepts. An event stream is similar as behavior, but it is
a stream of discrete events instead of continuous values. But you
don't have to worry about that. It's just another object which has
slightly different API. A higher order event stream is an event
stream of event streams. This is used to make a stream which behavior
is switched depends on the input.
This mouseDownMove makes a higher order event stream that
tracks mousedown and
mousemove. extractEventE(element,"mousedown") extracts
mousedown event in the element. When the event signaled, the function
inside the mapE is evaluated. MapE is similar
as liftB but it is only for an event stream. Inside the
function, extractEventE(document,"mousemove") find mousemove
events and track the distance from mousedown. Note that I
used document to find the event because occasionally you drag
a mouse to outside the widget.
function mouseDownMove (element) {
return extractEventE(element,"mousedown").mapE(function(md) {
var initValue = parseInt(element.value);
var offset = md.layerX;
return extractEventE(document,"mousemove").mapE(function(mm) {
var delta = mm.layerX - offset;
return Math.max(1, Math.round(delta / 20 + initValue));
});
});
}
We need to handle mouseup event also. The mouseUp
function returns a higher order event stream that find mouseUp event
and the zeroE happily does nothing.
And these two event stream make by mouseDownMove
and mouseUp are going to be merged by the
mouseDownMoveUp function to complete a mousedown, mousemove,
and mouseup cycle. MergeE is used to merge two events
streams. We need one more step switchE to convert a higher
order stream to a nomal stream, in this case, a stream of numbers
(distance).
function mouseDownMoveUp(element) {
var downMoveUp = mouseDownMove(element).mergeE(mouseUp(element));
return downMoveUp.switchE();
}
Finally, we connect the event stream into an HTML element. Here I
did slightly dirty work. Whenever a drag gesture happens, the
element.value attribute is set. Probably
using insertDomB to make an output element is cleaner way,
but I chose this dirty way to make it simple. At the last line, the
event stream is converted to a behavior object
by startsWith. And that's how makeAdjustableNumber is
implemented.
function makeAdjustableNumber (element) {
var drag = mouseDownMoveUp(element);
drag.mapE(function(n) { element.value = n; });
return drag.startsWith(element.value);
}
Honestly, Flapjax doesn't seems to be too easy to use. But part of
the reasons might be that I chose to show a plain Javascript syntax to
introduce the mechanism. Flapjax also provides its own compiler which
provides cleaner syntax. This Flapjax syntax should improve
readability a lot. Anyway, I hope this short note helps you to grab a
brief idea of Flapjax and FRP.
First post this year, yikes! The last one was about ESUG 2010 in Barcelona, now I just returned from ESUG 2011 in Edinburgh. While I was there, a package with the shiny new XO-1.75 prototype arrived.
Incredibly, the pre-installed Etoys simply worked! Never mind the change in processor architecture, the Fedora folks have done a great job compiling the Squeak VM for ARM and so Etoys just works. Of course that's just as it should be, but it's still awesome. And e.g. Squeakland's own Etoys-To-Go would not have worked, as it only includes binaries for Intel-compatible processors.
Another great addition is a 3-axis accelerometer. The Linux kernel's driver exposes it as a file at /sys/devices/platform/lis3lv02d/position. Gotta love the unix design of exposing devices as files. All it took to make this usable from an Etoys project was just an object with ax, ay, and az variables that get set with one simple textual script:
Another simple script can use this to control a ball (the "rebound" script just keeps it on-screen):
Fun all around—it's a bit a hard to see the yellow ball in the Video, but Jakob enjoys it anyway: Also, uploading from Etoys directly to Squeakland using Wifi just worked. Yay!
Update: If you want to try my uploaded project on your XO-1.75, you need to save it once from Etoys, quit Etoys, and run it again. Otherwise it won't work - it was signed by my key so the Etoys security sandbox prevents it from opening the accelerometer device. The saved copy will be signed using your key so no sandboxing happens.
by Bert (noreply@blogger.com) at November 01, 2011 01:31 PM
Bret Victor came to our office
yesterday, and we had a great chat. He is a great thinker and has a
beautiful sense about visualizing abstract ideas. I really like his
works. I want to learn his idea more, but as a starter, I tried to
implement his early
famous Alligator
Eggs! game. This game was made to teach about lambda calculus to
eight years old kids. But it's even more fun to adult hackers!
This is a green alligator and her egg. This family shows a lambda
expression λx.x (because I know you are not an eight years old, I use
formulas without hesitation!). There is a no animation as there is
nothing to eat.
But things are getting fun when there is something to eat before
the alligator mother. In this case, a blue egg. If you click on the
diagram, you see what's happening (I only tested Chrome, Safari, and
Firefox). The alligator eats the poor blue egg. But price for the
sacrifice is too high. The mother will die, and we will see the
new baby.
And then, things are getting curiouser. The new baby doesn't look
like the mother at all, rather it is like a blue egg, the victim of
the slaughter. What's a amazing nature of the lambda land!
This is slightly a hard example. There are two alligators "x" and
"y", and two victim eggs "a" and "b" on the right side. If there are
more than two things next to an alligator, the alligator eats left one
first (it is called as left associative in jargon). Can you guess what
does happen after the meal? Alligator "x" eats egg "a", and alligator
"y" eats egg "b". And only egg "a" survives (because it transmigrates
through the green "x" egg).
You can think that this alligator family (λx.λy. x) eats two
things and leave the first one. In a same way, can you think of an
alligator family which eats two things and leave the second one? Here
is
the answer.
There are a few things to know more. Old alligators are not
hungry. But they keep guarding their family while they guard more than
one things. They behave like parenthesis in a lambda expression.
This rule is the most tricky one. There are two blue alligators "y"
at left and right, but those two are not in a same family. The only
mother of the blue egg "y" is the right one. It gets trickier when the
family is eaten by the green alligator because the blue family is
reborn at the green egg is, where is bottom of another blue
alligator. To make them different, the right blue family change the
name and color to "y1" and orange.
By these rules, you can make various kinds of alligator
ecosystem. This is my favorite one. (λx.x x) is called a
"Mockingbird" or, rather we should call it Mockingalligator. It
doubles its prey twice. So what happens if a mockingalligator eats a
mockingalligator? The result is called one of omegas, an infinite
loop. They are eating forever. To stop the endless violence, please
click the diagram again. But please do not to click three times!
Because of my bug, something wrong will be happening.
This is dangerous but beautiful one. The omega ecosystem above kills each
other but it doesn't make any, but this Y combinator is very
fertile. It produce many, so you have to watch it carefully, otherwise
it consumes all the CPU power you have eventually!!
Actually, alligators also can do serious jobs. If you design
carefully, you can teach them how to calculate 3 + 4! In this example,
the middle family represents three and the right family represents
four (count green eggs). And the result is a family with seven green
eggs! This is
called Church
numbers (I don't have a time to explain the theory, so please read
the link).
I only introduced very few alligator families. If you want play it,
visit
http://metatoys.org/alligator/
and design by your self. You can also download from
http://github.com/propella/AlligatorEggs. The
source code is messy because I haven't written javascript recently,
but I'll clean it up soon.
by Takashi (noreply@blogger.com) at September 23, 2011 02:51 AM
If you have played with Etoys, you might have seen The Etoys
Castle (or The Demon Castle) tutorial. But you would never know how
the story ends, because the Etoys distribution only includes the first
chapter, and the last slide shows "To Be Continued ...". However,
there are actually the hidden sequels, and the story has a happy
ending.
When I first wrote the story in 2006, there were three
chapters. The first chapter was about learning "handles", the second
one was about the painter, and the third one was about scripting. But
due to some technical issues, I gave up to publish them. Today, I
happened to clean up my hard drive and I found old files. It's shame
that I have never published rest of them. So I gathered the screen
shots and made up one page html.
by Takashi (noreply@blogger.com) at July 10, 2011 02:24 AM
Tinlizzie Wiki is a wiki written in Tweak. It uses OpenDocument Format
(ODF) as data format, and WebDAV as server.
Although data format in StackWiki was Squeak specific binary, In
Tinlizzie Wiki existing common format is used. A part of reason why I
choose ODF was that it was a research project to find a possibility to
exchange eToys content among different platform. So it was necessary
to find platform independent and transparent format. ODF, especially
its presentation format, was quite close to my demonds which are a)
text based b) enable to embed graphics c) enable to use original
element d) internal and external link supported.
A ODF file is just a zip archive which includes XML text and
multimedia binary files. And it is easy to extract image file in a
project by an another tool. Both embeded object and external resource
can be represented by common URL notation. And if necessary, new tag
for Tweak specific object can be used. For example, a project which
includes fully dynamic behavior written as Tweak objects can be viewed
on ordinary OpenOffice Org application, although dynamic feature would
in it be disabled.
To export Tweak object to ODF as natural as possible, special care was
needed to save. It is not the best way to define a new tag for Tweak
specific object even though it is possible. It was preferable to map
from Tweak to ODF properly. For example, if a Book object in Tweak is
stored as a presentation within frame in ODF, the project looks
somewhat more normal even on other application.
There is a issue how much detail information is needed to save an
object. For example, if a text is saved during its editing, whether if
position of the cursor should be saved or not?? There are two strategy
in terms of implementation. One is to save everything except specified
status (deep copy), another one is to save only specified
status. Tinliziie Wiki adopted the latter one although Squeak and
Tweak native serialize mechanism were the former.
Saving only specific status has two disadvantages. a) A user might
expect to save everything including minor information because
combining arbitrary objects in even any peculiar way is possible in
Tweak. b) Each new widget needs to implement each exporter. But
"saving everything by default" strategy has a problem of compatibility
because even just one change of variable name makes trouble for old
version. Especially it is problematic for sharing in Internet. So I
din't choose this strategy.
WebDAV is used as the server. Both StackWiki and Tinlizzie doesn't
need server side logic, but simple storage is required. WebDAV is the
best option for that matter. Even version control system can be
plugged in the server with Subversion modlule in Apache for free,
Javascript Workspace is a simple web application. It uses bare
Javascript on client, and Ruby CGI on server. It behave like a
Smalltalk Workspace, and the contents are managed same manner as Wiki.
Let me make sure about workspace again. Workspace is a text editor,
and it has two additional commands "do it" and "print it". Do it
command envokes a source code selected by user, and print it command
output the result into cursor position. The function is similar to
REPL shell on dynamic language, but the use case is slightly
different. A typical way to use workspace is as an explanation of
program. An author writes example source code inside the
documentation, so that a user can try actual function while reading a
text. Namely, REPL is two ways dialog between a machine and a human,
but workspace is tree ways conversation among a machine, an author,
and a user.
Workspace is indispensable tool for Smalltak though, which doesn't
mean only for Smalltalk. It would be nice if there is a workspace for
Javascript language. This was the initial motivation of Javascript
Workspace. And then, it was a natural consequence that Wiki was used
to save the content because Javascript lives on web browser
intrinsically, and there are no way to save to local disk.
During the development, however, I realize that it can be more than
just a workspace in terms of media. Javascript workspace has only
simple user interface, which includes a couple of buttons and one big
text area. Even there are no hyper link nor emphasized text. But
variety things can be happend from such minimal configuration by
source code. Hyper link is enable to make from location property, rich
text can be shown to modify DOM tree, and even game can be made to set
up event hander. Source code can do everthing.
Just one textbox on a web page is a very radical idea. This is
completely opposite direction to current trend of rich internet
application. Web application consists with number of hidden functions
these days, but Javascript Workspace can not have any invisible
information. Everything what it does is shown to you as source code
entirely on the screen. Javascritp Workspace looks like dangerous as
it runs any Javascript code, but in fact, it is a quite safe system.
The idea of uset interface of Javascript Workspace is adopted to
OMeta/JS.
TileScript
TileScript uses Scriptaculous as GUI library and WebDAV for server
storage. JSON is used for its data format.
A TileScript document consists with one or more paragraphs, and a
paragraph is either Javascript code, "tile script", or HTML
expression. A tile script is set of tiles, which each tile represents
some syntactical element in a programming language. A user can connect
tiles to construct a program with drag and drop. This is an easy way
to make a program avoiding syntax error. Javascript is used to
represent more complicated program than tile script. And HTML is used
as annotation. It can be seen as rich version of Javascript Workspace.
The initial motivation of TileScript was to remake eToys on the web
environment. The research had got started by making tile available on
web browser. I considered to use Lively Kernel (SVG), but it was
unnecessary if Table element in HTML DOM is used as
tile. Scriptaculous is used to keep the source code simple.
After tile is ported, then next step was eToys environment itself
which includes event handling, scheduling, and bitmap animation,
etc. But those issues seemed too difficult for nature of web document.
Flow layout, which actual position of document elements are
dynamically changed by reader's browser environment, is a significant
feature of web. An author don't specify concrete position of elements,
but rather care about logical structure. And then, a part of document
which can not be shown on the screen is accessable by a vertical
scrool bar.
On the other hand, eToys provides page layout, which size and position
of elements is fixed, and presume particular screen size. Althogh, it
is quite fit as a metaphor of physical paper, and best for a graphical
environment like eToys, but clumsy operation like zooming and
horizontal scrool is required.
Because ultimate goal of TileScript was not just reinventing eToys,
but investigating further possibility, flow layout is adopted to
TileScript. But still absolute coordination can be supported in form
of embeded object even in flow layout. TileScript provides variable
watcher like eToys, but those widget is also layouted along with flow.
And then
Now I'm working on next version of Javascript Workspace, which
especially its target application is Active Essays. Our group have
found that Javascript is quite reasonable tool to show some ideas of
computer science. One reason is language's simplicity, and other one
is easiness of collaboration. We have a lot of new ideas about
programming language, and some of the part should be simple enough to
understand even by junior high student. I believe my tool can be used
to explain such ideas.
The problem is any project intoroduced here is not intended for real
use, rather just for demo or prototype of further real development. So
it is not be so useful as it looks because it includes too
experimental aspect, too fragile, or too slow. Now I'm thinking that
it is not bad idea if I make somewhat stable version of them. Even it
might not have exotic feature like tile script, but only basic and
simple functions are enough to play with everyone. I really like my
first idea of Javascript Workspace, which has only simple text. I
admit it is extreme, so next version might support emphasized text and
inline image (basic HTML elements) at least.
by Takashi (noreply@blogger.com) at June 30, 2011 09:54 PM
Glad to invite everybody to register for exploring now the OpenQwaq's collaborative 3D forums using Krestianstvo SDK2 and ongoing Krestianstvo's 2 forums (CCSE, Learning math, Collaborative music, Art disks, ect.) in near future. The registration page is available online now for all: http://www.krestianstvo.ru/register (RU: http://неучи.рф/регистрация ). As soon as you get the Login and Password, you could enter into the collaborative 3D forums anywhere through the internet. But for that you'll need to download the new version of SDK.v.2.0.2: here or using an alternative link, or update the 2.0.1 one (Monticello repository here: http://krestianstvo.ru:8888/sdk/Monticello/sdk2/). The main feature of the new 2.0.2 SDK is the new database storage logic, entirely based on XML and taking away the ODBC/MySQL usage. So, the OpenQwaq's service provider (not the Local's one) use the XML based db just as MySQL db, while storing it in Smalltalk class variable and serializing it's tables onto disc with plain XML files. That scenario is suitable for local and internet servers, thus turning OpenQwaq onto really mobile platform. Another feature is directed against Apache/PHP, meaning the coal/web/forum services running on :9991. So, the first step you could look at working online registration on Krestianstvo site and next will be having all admin pages using just Javascript and Ajax, hosted on the same Smalltalk image.
See you in the forums!
by Suslov Nikolay (noreply@blogger.com) at June 18, 2011 10:39 PM
OpenQwaq is the most awaited framework in the virtual world's development domain! Four years left after the latest OpenCroquet release and OpenCobalt has done a lot to bring virtual worlds closer to life, but OpenQwaq set the final point! Now anybody could set up it's own virtual space or forum and do not worry about the underlying network architecture, just create Forums, create content for them and place on the servers through the web and collaborate. So, everything looks just fine, but... to start own server on LAN or WAN someone need to install Linux, Apache, PHP, MySql and OpenQwaq server itself following config rules and avoiding the pitfalls. But hey? We are in Squeak/EToys platform, Smalltalk at last.. in the self-contained environment, so why all these third-party tools a needable? (Yes, for: Security reasons, Application services, Streaming, account politics ect). But in learning situation at classroom or in Art gallery during installation all of these features are not too critical. I decided to explore, how it is possible to have just One-Click OpenQwaq image with server and client on it, that could run as internet or local server or just a client. Image, that in a few clicks could be used by children setting up the classroom's network or artists making performance / installation. And the Krestianstvo SDK 2.0 as experimental platform was borned! Comparable to OpenQwaq, I started Krestianstvo2 with only one image for server and client versions (the server one based on Squeak 4.2). The aim is to start the server with no need of installing any other third party applications (apache, mysql). Of course, some (a lot of) features of OpenQwaq could not be available in such scenario, but the work is in progress... In the current version, anybody could easily setup the running server on LAN or WAN (the server http://www.krestianstvo.ru has already running the same image as provided for download). SDK is developed on top of OpenQwaq, so that no part of the original OpenQwaq code in image is modified from the functional point of view. So, SDK image allows to run OpenQwaq Forums just in pure mode. Nevertheless, for localization purposes the String method #translateMe was introduced and was injected into OpenQwaq code for the most of string's objects. Translation process is still in progress too. SDK works with Russian language support by default! ---------- Try out the running space! The demo logins and passwords, that's working on krestianstvo.ru
Login: member Password: member Organization: krestianstvo Server:kresianstvo.ru
Login: guest Password: guest Organization: krestianstvo Server:kresianstvo.ru ----------- You could add as new members and new groups in setup, visually. In main login screen use right mouse button to have the context menu and select: "Add new user...".
Example connection scenario:
1. On the 'A'host you start Krestianstvo with as server (type instead of krestianstvo.ru the in the 'Server:' field). 2. On the 'B'host you start Krestianstvo with IP address of 'A' host as server. 3. Then try to login with l: admin/p: admin (l: member/ p: member) accounts (or add new members in 'A' host (on the main login screen, where is proxy configuration dialog).
So, in final it will be good to have: CoalServices working with local storage database in memory (instead of mysql) with Smalltalk WebServices front-end (instead of apache/php).
And now, it is burning at the Wikipedia stake: just here. The judges are economists, lawyers ect., analyzing the article by formal criteria like spam-bots.
This definitely prove to me, that Krestianstvo is going the right way!
by Suslov Nikolay (noreply@blogger.com) at March 09, 2011 08:07 PM
Here is a video from the recent event, which was held in the "Museum of Science" (Russia, Vologda), where the Multi-touch table based on Krestianstvo SDK was shown. The table is controlled directly by Krestianstvo virtual space and it's objects shared on the Croquet island. So, several such tables could be organized into p2p network and become a really interactive classroom, programmable just in Smalltalk. For recognizing reacTIVision fiducial markers and TUIO protocol are used (based on Simon Holland TUIO for Squeak work). For music synthesising SuperCollider through OSC is connected, using the idea from SCIMP (SuperCollider Server client for Impromptu) and realized in Smalltalk.
by Suslov Nikolay (noreply@blogger.com) at December 28, 2010 08:53 PM
Want to share my early experiments with the novel controller from Microsoft: Kinect, fine working in Krestianstvo SDK (based on Smalltalk dialect Squeak/Croquet). Here you could find an interesting list of projects and ideas already evolving using Kinect in different programming languages (c, c++, of, max/msp, processing. java, ect.) But, why not in Smalltalk?.. And in pure 3D Virtual Space (Croquet), controlling your Avatar with own body and operating on objects just with own hands.. So, using OpenKinect driver, I prepared the plugin KinectSqueak.framework and the changeset for Krestianstvo (source code is avaliable here) with Mac OS X support only for now (Window will be very soon). The latest downloadable SDK is also include Kinect support, so just download it and try the sensor, if you have one..
Happy Kinecting!
by Suslov Nikolay (noreply@blogger.com) at November 26, 2010 01:04 AM
Happy to announce an October update of Krestianstvo SDK with it's main feature: World serialization support
Meaning, that one could freely save a current work, being done in active space and then restore it at any time later. The spaces are saved into OWML text file format (check them in Resources/resources/MySpaces folder). In the next post, I will write an introduction to this new format. Briefly to say, it is mainly based on Sophie XUL and partially C3X serialization logic.
Some other features: new objects (Text3D), Seaside and Squeak base image update, Cog VM update, UTF-8 encoding is default in Mac VM now.
Happy serializing!
by Suslov Nikolay (noreply@blogger.com) at October 25, 2010 09:52 PM
Tamacola is not just another LISP language, it is designed as a
meta-language to make a new language. I'll explain this feature today.
Today's goal is to design a subset of lisp language. If you think that
a lisp is too simple to keep your passion, sorry, be patient, simple
thing first.
Prepare your Tamacola environment
To setup Tamacola environment, you need to download both Tamacola
distribution and Tamarin VM. Those are available on
http://www.vpri.org/vp_wiki/index.php/Tamacola. You
need add the PATH environment variable to find the avmshell command,
and also it would be useful to set the PATH to bin/ in the tamacola
tree.
To make sure Tamacola works, plese type:
make run-example
It runs all of the examples in the Tamacola distribution as well as
recompile the compiler. If you don't find any error, you are ready to
go. Otherwise, please let me know the problem.
Tamacola command
Tamacola command read a tamacola program and run immediately. If you
want to make a Flash contents, another command tamacc (Tamacola
Compiler) is more suitable. Now we are playing with an interactive
shell of tamacola command, so I'll give you a brief explanation.
The interactive shell starts with minus (-) option. Let's try a simple
arithmetic. If you didn't setup PATH environment, please specify the
directory name, too.
$ tamacola -
Cola/Tamarin
> (+ 3 4)
7
You can also give Tamacola source files as well as compiled binary
names. Typically, source code ends with .k, and a binary ends with
.abc. Tamacola is smart enough to detect newer file between .k and
.abc.
Match against a string constant
Suppose you are on some working directory, and you have already set
PATH environment to the bin/ directory. And then, we are going to
write a very simple language, greeting:
;; greeting.g - A simple PEG example
greeting = "morning" -> "Good Morning!"
| "evening" -> "Good Evening!"
This stupid example answers "Good Morning!" if you say "morning", and
it answers "Good Evening!" if you say "evening". This PEG syntax is
easy to understand. The right hand side of = is a rule name. A rule
name is translated as a function once it is built. -> means an action
rule, where if the left hand is matched the right hand side is
returned. | is an Ordered options. In this case, the parser tries the
first case "morning", and tries the second case "evening" only if the
first case fails.
Save this syntax named "greeting.g". To test this language, type those
commands:
Mkpeg command converts grammar file (greeting.g) to tamacola source
(greeting.k), a rule "greeting" the result can be read by tamacola
shell. Greeting.k is built on the fly and the command prompt is shown.
Parse-collection's first argument is a parser name (in this case
"greeting"), and the second is a input collection. As the name
implies, it accepts any collection as the input stream.
The second case shows an interesting property of PEG syntax. Although
the second rule matches the beginning part of the input "evening
tokyo", still the input remains more string " tokyo". PEG doesn't care
if the input is competely consumed or not. If you really want to make
sure that the entire input is matched, you need to explicitly tell the
Parser the point where end of the file.
Number parser
The last example only matched a predefined constant, but we make a
parser for any integer number here.
;; number.g -- A number parser
digit = [0123456789]
number = digit+
We also convert the grammar specification into the tamacola program,
but in this case, we give -n option to tell the namespace. A namespace
is useful when you want to use a common name as a rule name like
"number". Because "number" is already used in the system, you can not
use it without namespace.
The grammar itself is easy to understand if you have an experience
with regular expressoins. Brackets ([]) matches one of characters
inside, and postfixed plus (+) repeats previous expression with
one-or-many times.
Because we use the namespace "number", we need specify the
namespace before slash(/) in the function name.
As you might notice, this parser correctly rejects a non-number like
"xyz", and accepts "345". But the result is not so useful. The return
value of plus is a special object named "token-group", but we would
want a number represented by the string, instead. So we put a
conversion function to get the value.
number = digit+:n -> (string->number (->string n))
Now parser returns a number conveniently. Perhaps you might think that
it is somewhat cheating. As the string->number function itself is a
kind of number parser, we should have write a number parser without
string->number! Yes we could. But it leads more interesting topic
about left and right recursion, so I leave it for later.
S-expression parser
Now we are going to write a parser for almost real S-expression. This
parser can only handle number and list, but it is useful enough to
explain the essence of Tamacola.
In this grammar, only new operator is the postfix star (*) which
repeats zero-or-many times. Rest is straightforward. To test this
grammar, we use Tamacola's simple test framework. Writing test case is
better than the interactive shell, because you don't have to type same
expression many times.
The check function comes from SRFI-78. This function complains only if
the left hand value and the right hand value differ. Otherwise, does
nothing. I like this UNIX stile conciseness.
As a convention, a test program is added a postfix "-test" with the
main program's name. I borrowed this custom from Go language.
Make sure this program do nothing.
$ tamacola sexp.k sexp-test.k
Lisp Compiler
The PEG parser can handle any list structure as well as string. It
allows you to write compiler in PEG. In a string parser, the input is
a string and the output is some object (a list in our case), but in a
compiler, the input is a lisp program and the output is a assembler
code.
There are some new elements in the grammar. Quoted list '( ) matches a
list structure, and a quoted symbol matches a symbol.
A prefix ampersand (&) prevents to consume the stream even if the rule
matches. For example, &arity rule examine the rest of the list, but
the contents are matched again by the insts rule later.
Is-number is matched against number, and is-symbol is for a
symbol. Those rule can not be described as PEG grammar, but as a lisp
function.
A rule is a function which receives the stream and the parser (an
object which store the result). The rule function returns #t if it
matches, and #f if it fails.
I think it is easier to see the test code than read my explanation.
You can read the entire program in example/sexp.g in the Tamacola
distribution. To try the program, please enter:
make -C example test-sexp
Left recursion
We left an interesting topic about left and right recursion. Let me show you our number parser again.
digit = [0123456789]
number = digit+:n -> (string->number (->string n))
If we don't want to use string->number function, I would write the parser as:
;; Use fold-left
digit1 = [0123456789]:d -> (- d 48)
number1 = digit1:x digit1*:xs -> (fold-left
(lambda (n d) (+ (* n 10) d))
x
(->list xs))
Digit1 rule converts the ascii value of the the digit character,
and number1 rule construct a decimal number. As you see, you need to
use fold-left function to construct a number because a number notation
is essentially left recursion. For example, a number 34567 actually
means:
(((3 * 10 + 4) * 10 + 5) * 10 + 6) * 10 + 7
However, PEG parser doesn't parse left recursion grammar in
general. So I had to reconstruct the left recursion structure by
fold-left. This is not hard at all if you familiar with functional
programming. In functional programming, a list is considered as a
right recursive data structure and it is even natural that a list is
parsed by a right recursive way. However, I admit that it looks
awkward for some people.
Yoshiki Ohshima provides a very useful extension to support a direct
left recursion. To use his extension, the number parser is written as:
;; Use left-recursion
digit2 = [0123456789]:d -> (- d 48)
number2 = number2:n digit2:d -> (+ (* n 10) d)
| digit2
number2s = number2
You need to load runtime/peg-memo-macro.k to use this extension.
The real parser and compiler are bigger than presented grammars here,
but I explained all of the essential ideas. I hope it helps you to
make your own language!
by Takashi (noreply@blogger.com) at October 04, 2010 09:38 PM
This year's conference logo was designed by my good friend Patty Gadegast.
I just returned from the European Smalltalk User Group conference in Barcelona, Spain. It was a really nice experience. There was too much going on to report everything here, so I will just pick some favorites.
Photo by Bert Freudenberg
The event was hosted by citilab Cornellà. It started off with a Camp Smalltalk over the weekend. I already met quite a few people there. I couldn't mingle as much as I hoped to because I had to get the first Etoys 4.1 release candidate out of the door:
Close by was "Yokohama Wok", a Japanese/Spanish restaurant with the best all-you-can-eat buffet imaginable. You could have everything from freshly cut ham to sushi, grilled steak or seafood, bread, pasta, rice, fruits, cake, desserts.
Photo by Bert Freudenberg
I talked to Stef (president of ESUG) and gave him a Squeak Etoys button, which he ended up wearing the whole week:
Photo by Bert Freudenberg
We also played together in a 2-on-2 Magic game (which we promptly lost ...):
Photo by Bert Freudenberg
On Monday I gave my Squeak Community Update talk, outlining what has happened in the Squeak and Etoys communities lately. Got some nice comments afterwards, including the request to give an Etoys demo the next time. I of course used Etoys to give the presentation, but did not really include an Etoys introduction for people who had not seen it before. But I got a slot in the "show us your projects" session on Tuesday where I made up for that with a 10 minute demo.
I was session chair on Wednesday morning, so I could see Travis' update on Pango text rendering from the first row. Would love to have that in Squeak, but it only builds easily on Linux:
Dale showed the beginnings of Bibliocello, a repository for Monticello packages that can actually analyze them. You get to search implementors and senders across all packages, take statistics etc.
And at the end of the day, an exciting demo was given by HwaJong Oh, a Smalltalker and iPhone developer from Korea. He demonstrated Drag-and-Drop for Squeak Tools, e.g. dragging the object held in an instance variable directly to another inspector.
I have published the source code of Tamacola, a lisp compiler which
runs on Adobe Flash / Tamarin VM (or Adobe Virtual Machine 2) http://github.com/propella/tamacola. I'm
pretty sure that the current version is useless if you are just
looking for a lisp implementation on Tamarin (las3r and scheme-abc are
much better), but Tamacola includes abundant tips if you are
interested in making a self-hosting compiler on Tamarin VM. That's why
I decided to publish it as-is.
I'm also working on a presentation slide for S3 conference
http://www.hpi.uni-potsdam.de/hirschfeld/s3/s3-10/ to show it. I'm writing
random thoughts about the compiler here so that I will compile them to
a thread of talk.
I've already written the motivation on the paper (perhaps I will paste
the URL in a month) so I don't repeat it. But in short, I wanted make
a tiny language which bootstraps and runs on Adobe Flash.
A tiny language and bootstrapping seem contradicting idea as
bootstrapping requires various language functions which tends to be
large. On the other hand, this is practically a nice constrain because
it keeps the language from too simple or too fat. Choosing Scheme like
language as a target is natural to me because I wanted to concentrate
basic implementation technique instead of language design.
Well, as one reviewer of the paper said, this is not particularly
surprising or dramatically different in comparison with previous
systems in the area, but some of the stories from the compiler should
interest you!
How I started the assembler
In the beginning I created the assembler. Honestly, I wanted to avoid
the task because writing assembler seemed not quite an interesting
job. But in that time, I couldn't find a nice AVM2 assembler that
suite my project. So I've done it. In retrospect, this was not bad at
all. I could understand what avm2overview.pdf (the AVM2 specification)
said quite well, and I got self confidence.
I wrote my assembler in PLT-Scheme because Ian Piumarta's COLA
(Tamacola was supposed to be written in COLA and Tamacola itself, I'll
tell you this later) is not finished yet in that time and Duncan Mak,
a friend of mine, recommend it. This was actually a good choice. This
is my first Scheme application and PLT's good documentation helped me
a lot.
An interesting part of PLT-Scheme was it encourages a functional
programming style, even PLT doesn't suppport set-car! and set-cdr! in
the default library. So it was natural that my assembler was written
without side-effect except I/O. This is the first key of the
development of the assembler. Unfortunately, because Tamarin doesn't
support tail-recursion optimazion and Tamarin's stack size is small, I
gave up to eliminate all side-effect later. But the implementation was
pure functional up to the time, and it was quite clean.
Indeed, it had to be clean considering boot-strapping. I wanted to
make the assembler run in my language itself even before enough
debugging facility is not ready. If it were not clean, a tiny bug
would cause a few days of debugging. I avoided the nightmare with a
functional style and Test Driven Development.
Test Driven Development is the second key. I virtually wrote every
test case for each function even if it looks silly. Scheme has a
couple of options of testing frame work. I chose SRFI-78. It only
report assertion failer only something happen, otherwise it keeps
silence. I somewhat like this UNIX taste terse.
The third key was to write an assembler and a disassembler in a same
time. It sounds like an unnecessary job because I only needed an
assembler eventually. But I had to analyze an output from asc (an
asembler in Adobe Flex) and learn how an ActionScript program was
converted to the Tamarin byte-code. The disassembler was very helpful
to read the byte-code as well as debugging. If output of the
disassembler generates the original byte-code by the assembler, there
is high chance that my imprementation is correct, unless my
understanding is wrong.
The assembler is named ABCSX http://github.com/propella/abcsx
and it was ported to Gauche, COLA, and Tamacola later. I ported it to
Gauche because I was curious about portability of Scheme language.
I had realized there are many places where I could reduce code
redundancy in the assembler. An assembler tends to include repetitive
process, but some of them are not quite captured well by function
abstraction. I would be effective to apply macro and domain specific
language in those part. I didn't have tried to solve it yet, but I
want to solve it later.
(to be continued)
by Takashi (noreply@blogger.com) at September 24, 2010 07:51 AM
After I made the Tamacola compiler written in COLA, next thing to do
was to implement it in Tamacola itself. A language is called
self-hosting if the language is written in the language itself. This
implies various advantage.
First, once self-hosting is done, you don't need to use COLA anymore,
you can improve or modify any language aspects on Tamarin VM. If I
carefully design the environment, it would be possible to do language
design only on the Web browser (it needs server side help for security
reason, so it hasn't done yet).
Second, self hosting is a benchmark for the language to tell that it
is good enough. Scheme is especially simple language, so there are a
lot of people who implement toy-Scheme. But because my Tamacola is now
self-hosting, I could proudly claim that this is not a toy! Well, this
is rather self satisfaction, though.
Third, it provides a rich library including "eval" function. A
compiler uses various programming techniques, and those must be useful
for other programs, too.
To make it self-hosting, there were two key problem which are macros
and eval.
Bootstrapping Macros
I heavily used macros in my compiler, for example, the parser written
in PEG was converted a bunch of macro expressions. The problem is,
expanding macros requires eval function but I wasn't able to make eval
before the parser was done. It's a deadlock! Here is a typical macro
written in COLA:
(define-form begin e (cons 'let (cons '() e)))
This is how the macro works. When the compiler find a expression like:
(begin
(print "Hello")
(print "World"))
Expressions inside begin is bound to e, the
body (cons 'let (cons '() e)) is executed in compile time
and the expression is expanded to:
(let ()
(print "Hello")
(print "World"))
Such expansion is impossible without eval function because the
compiler need to evaluate a list (cons 'let (cons '() e))
given by user. What I would do when I didn't have eval yet. But I
realized that macros only include basic list functions like car, cdr,
and cons in many cases. And a more complicated macro could be hard
corded as a special form in the compiler. So I invented a pattern base
macros.
(define-pattern ((begin . e) (let () . e)))
Basically this is a subset of Scheme's syntax-rule. If the compiler
finds an expression starting with begin, rest of the
expression is bound to e and substituted as a right hand
side. Those expansion requires only limited set of list functions, so
the compiler doesn't have to provide full eval function. This macro
syntax made my compiler readable, and I was able to continue happily.
Even after I implemented more dynamic traditional macro with eval
function, I keep using this pattern base macros mainly.
Eval
To implement eval function, you need to understand the dynamic code
loading facility provided by the VM. Note that this is not part of
AVM2 specification, and Avmshell (a console Tamarin shell program) and
Adobe Flash have different API.
Avmshell has straightforward API. You give compiled byte code, and the
function returns the value. Because Tamacola is now written in
Tamacola, you can invoke the compiler as a library function and get
byte code you want to execute.
avmplus.Domain.loadBytes(byteArray:ByteArray)
You can get the domain object by Domain.currentDomain() static method.
Those useful functions in Avmshell are found shell/
directory in the Tamarin-central repository.
Flash Player has somewhat tricky API for dynamic code loading. The
signature is normal.
There are two problems for our purpose. First, this method is not
designed mainly for dynamic loading, it only accepts SWF, JPG, PNG, or
GIF files, and byte code happen to be accepted inside a SWF file. So I
had to construct SWF file to load code. In case if you don't know
about SWF file, SWF file is a kind of container format. You can
embedded vector graphics, mp3 sounds, and ActionScript byte
code. Making a SWF file is not particularly difficult though, it needs
nasty bit fiddling.
Second, this is far more problematic, is that this method works as
asynchronously. In other words, this doesn't return the result
value. Instead, you need to give it a callback function to wait to
finish the code. Additionally, this method doesn't return value at
all, so if you want the return value, you need to setup some explicit
return mechanism by yourself.
Practically, this cause a problem if you want to write a traditional
macro definition and use the macro in a same source code. Because a
traditional macro need to evaluate a lisp expression in a compile
time, but the eval function doesn't return before the compilation
thread is done. I could solve the problem by setting up compilation
queue or something, but it would cost performance penalty which I
don't want. And now I simply gave up.
I have explained pretty much all interesting aspect of the self
hosting compiler. I'll talk about how to make a new language on the
Tamacola environment later.
by Takashi (noreply@blogger.com) at September 16, 2010 05:47 AM
Now I'm going to talk a bit about how a lisp (almost Scheme) program
is compiled into Tamarin's byte code. This topic is especially
interesting if you are curious to make your own language or VM.
Tamarin VM is made for ActionScript, so its byte code is also
specifically designed for ActionScript. In other words, it is a
slightly tricky to implement other language than ActionScript. In
case if you don't know about ActionScript, it is almost identical as
JavaScript in the execution model. Difference between them is about
optimization with explicit type notion and static field.
ActionScript and Scheme are common for those aspects:
Lexical scope.
Function object.
Variable arguments with no curring.
Dynamic typing (a value has type, not variable).
But there are significant difference.
ActionScript doesn't have a simple function call. Everything is a method call.
In ActionScript, a function has a scope. No scope block or let expression.
Tail call optimization is not supported.
Call stack can not be accessed.
Those limitations sound like that Tamarin VM is inferior. But no,
actually those limitations come from Tamarin VM's advantage and
optimization. If you happen to have a chance to design your VM, please
learn from the lesson. There ain't no such thing as a free
optimization. Any optimization kills some generality. I'll explain each
case.
ActionScript doesn't have a simple function call neither Tamarin
VM. This is rather harmless though. When you see a function like
expression like trace("hello"), this is actually mean
(the global object).trace("hello"), and eventually, the
receiver passes to the function as the first argument. In other words,
if you want to construct a function call with two arguments, you need
to make three arguments where the first argument is "this" object. A
slightly tricky part is primitive operators like + or -, which don't
have "this" object. Those primitives are special case.
ActionScript also has lexical scope, but only a function has a
scope. So I have to be careful when I compile let expression in
Scheme. Most simplest way to implement a let expression is to use a
function. A let expression can be always translated to a lambda in
theory though, this is a huge performance disadvantage. So I use
"with" expression in ActionScript. "With" expression is an unpopular
syntax in ActionScript, but you can use any object as a scope
object. I borrowed this idea from Happy-ABC project http://github.com/mzp/scheme-abc.
Lack of the tail call optimization in Tamarin VM was the most
disappointed thing to me. It prevents a functional programming
style. I simply gave up it. Tail call optimization is not difficult
topic at all. If the target were a native code like x86, it would be a
matter of swapping stack and jump. But Tamarin VM doesn't allow direct
access of stack or jump to other function. I understand that it might
cause a security issue though, it would be wonderful if VM would provide
special byte code for tail call.
Finally, you can't access the call stack directly, therefore you can't
implement call/cc. The reason why I can't call Tamacola as Scheme is
the lack of tail call optimization and call/cc. It prevents many
experimental language features like generator, process, or so. But
considering rich libraries provided by the Flash API, I would say
Tamacola will be a reasonably useful language eventually.
I'll tell you convolved self hosting process and macros tomorrow.
by Takashi (noreply@blogger.com) at September 15, 2010 06:04 AM
Once the assembler was done, I was able to test verious Tamarin VM's
features, even I wrote a tiny GUI application on Adobe Flash in the
assembler. Then next step is the compiler.
Another goal of the project was to port Ian Piumarta's COLA framework
to Tamarin (the project name came from this). And perhaps this is only
the real technical contribution of the project. COLA is a meta
language (a programming language to design another language) which
resembles Scheme. COLA has a nice sub-language called Parser
Expression Grammar that makes parser very terse. My plan was to write
a boot-strappng compiler in PEG and COLA, then to implement COLA
library, and to write the real compiler in PEG and Tamacola itself.
I won't give you the detail of PEG. But briefly, it is as simple as a
regular expression and as powerful as a context free grammar.
When that time I started writing the compiler, COLA has no library at
all except PEG framework, so I needed to write necessary libraries by
myself from scratch. Fortunately COLA has quite a powerful external
function call feature (a kind of FFI), macro sysytem, and a flexible
object oriented framework. So writing library is not so hard. But I
tried not to use COLA specific features as possible because it would
be a problem when I rewrite the compiler in Tamacola itself later.
To implement the library, I borrowed function specifications from R6RS
as well as possible to avoid unnecessary confusion. There were
exception because COLA treat a slash "/" character as special for
namespaces, I took PLT's function names in this case.
Writing lisp libraries is interesting puzzle to me because there were
some requirements and constrain for the domain. Those requiments are:
Unit testing framework.
Library framework.
List manipulations.
String functions.
Bit operations and streams.
Pretty printer for debugging.
These requirements were carefully chosen. Because COLA has only modest
debugging facility, the unit test framework must be there. So my first
goal was to implement all functions needed by the unit testing. I
needed a pretty printer for debugging, too.
Another "must have" library was bit operators, and file / in-memory
streams that is needed to the assembler. Interestingly enough, R6RS
doesn't define enough functions to support those. For example, there
are no portable way to specify a stream to be binary or text. So I
needed a bit creativity.
Eventually, I wrote all libraries and the compiler. And I got a pretty
good sense about a minimun set of functions needed for compiler, which
are testing framework, pretty printer, bit operators, and streams. In
other words, if your language has those features, your language can be
self-hosting.
The real puzzle part was the order. Those requirements must be
precisely ordered by need. For example, the pretty printer must follow
stream and string functions because the pretty printer uses those
functions. Although you can write functions in random order as you
like in Lisp, precise order makes testing and debugging is easy. I
kept this discipline. I even implemented the test library twice, the
first one was concise assert function, and the second one has more
friendly fail message by the pretty printer.
It took a few weeks to build a simple compiler, but still there were
long way up to the point where self-hosting can be done. One thing
that I had learned from the stage was, even without debugger,
debugging is not so hard if you have enough test cases and a good
pretty printer.
by Takashi (noreply@blogger.com) at September 14, 2010 04:43 PM
Below is the introduction video to the updated SDK:
[RU]
Рад сообщить, что отныне Крестьянство SDK работает на новой Cog VM (Windows Vista, Mac OS X 10.6, Ubuntu Linux 10.x проверены). Кроме того, представлен новый графический интерфейс пользователя, в том числе на русском и английском языках. Остров на остров соединения по локальной сети теперь работают, с возможностью запуска и из главного окна программы. Ошибки в OSC функциях исправлены.
by Suslov Nikolay (noreply@blogger.com) at September 13, 2010 01:54 AM
Tony Nemelka has just been named CEO of Teleplace and I couldn't be more pleased. I have had a number of discussions with him and some of the exceptional people he is bring with him since he started working with the company, and I am really impressed with his vision for the direction for the business and the clear focus he has on customer value. I am very proud that the company has been able to attract someone of Tony's caliber to be the CEO. No question that the company was ready for this next step. Greg Nuyens did an exceptional job positioning the company technically - Teleplace is the best collaboration platform in the world today, by quite a wide margin. Now it is time to leverage that technical advantage into a market advantage as well.
by David A. Smith (noreply@blogger.com) at August 20, 2010 01:02 AM
1. Working version of Collaborative Curved Space Explorer 2. Examples of Seaside 3.0 and Open Croquet integration in web browser with Comet support. 3. Examples of Collaborative coding trough web-browser on several images running Open Croquet 4. Open Sophie CSS/XUL logic for describing Tweak user interfaces. 4. Math examples on matrices and vectors in Krestianstvo's learning 3D space 5. OSC remote controlling support 6. 3d vision (red/blue) support 7. Tool for building multi-pixel projection walls or CAVE
and more..
Happy exploring!
by Suslov Nikolay (noreply@blogger.com) at July 31, 2010 03:45 PM
This is very experimental, but working announce. Open Croquet code from 1.0.18 SDK is now working in new Squeak 4.1 image and even ready to run on Cog VM.
In preparation of making Etoys work on the recently announced OLPC tablet, I ported it to the iPad. Here is a video—read on below for some details:
This might look exciting, and it certainly is, but it feels actually a lot more clunky than it looks. You may have noticed the little target circles I added whenever a finger touches the screen. That's to know where exactly the finger hit. It's really hard to hit anything, took me a while of training to hit the colorful halo handle buttons on first try. We really need to redesign the user interface before giving this into the hands of kids ...
But for now, some technical details: John McIntosh ported the Squeak Virtual Machine to Apple's touch-based OS last year (source available at isqueak.org). I modified it slightly to enable multi-touch and keyboard input. Also, I rewrote his code to deal with touch events in Squeak, and added multi-touch handling to Morphic. Fortunately, Morphic was designed to handle multiple "hands" (pointing devices) from the beginning, so adding this was much easier than in a system that assumes there is only one mouse. That's why moving multiple objects at the same time, and painting with more than one finger, just works once the events are in the system.
So far this is just an early test. We should work on improving the Etoys touch UI in next year's release. The Sugar menu bar works fine, but everything else is way too small. At least we have the luxury of being able to test Etoys already—getting the rest of Sugar running on a touch device might take a while. Hopefully OLPC will have developer machines soonish. If this test has shown one thing, then that there is lots of work to do (and it may even be necessary to start over).
by Bert (noreply@blogger.com) at June 21, 2010 09:16 PM
EN: There are recent great news from Etoys dev-list, that "Derek's new CameraPlugin morph should work on Windows, Mac and Linuxin Etoys image" :) And now it is available and working in Krestianstvo SDK as video window in 3D space (several camera instances support also). Online video is replicated to all participants of an island in realtime.
So to try, just update your recent image or download the latest SDK with CameraPlugin support in it. CameraPlugin binaries for Mac OS X/Linux/Windows are available here or could be found in Scratch distribution. When running Krestianstvo world, check the new item "Видео камера" in menu "Инструменты". Now everything is ready to:
develop the 3D stereo 'real world' vision support, using 2 video-cameras for left and right eyes, then
combine it with 'virtual world' stereo vision (already existed as 3D stereo filter) using some of video tracking technique, and
do all this in real-time
HappyVJeing!
RU: Прекрасные новости из Etoys листа разработчиков, что "новый Derek'sCameraPlugin может работать на Windows, Mac и Linux " :) И вот теперь он доступен и работает в Крестьянство SDK как видео-окно в 3D пространстве (с поддержкой нескольких видео-камер). Онлайн-видео репликацируется для всех участников соединения в реальном времени.
Чтобы попробовать, обновите систему по кнопке "Обновить" или загрузить последнюю версию SDK с поддержкой CameraPlugin в нем. Двоичные файлыCameraPluginдля Mac OS X / Linux / Windows можно скачать здесь или они могут быть найдены в дистрибутиве Scratch. "Видео камера" добавлена в меню "Инструменты".
Теперь все готово к:
1. разработке 3D стерео видения "реального мира", используя 2 видеокамеры для левого и правого глаза соответсвенно, а затем 2. его соединения со стереовидением в "виртуальном мире" (уже существуеющем в виде 3D стерео-фильтра), для этого использовать некоторые техники видео-трекинга 3. делать все это в режиме реального времени
Счастливого Виджеинга!
by Suslov Nikolay (noreply@blogger.com) at May 13, 2010 11:30 AM
About three months ago, I joined Lockheed Martin STS as their Chief Innovation Officer. I have been wanting to pursue a project that was quite different from the direction that Teleplace has been going, and after about a year of discussion, it was clear that the direction I wanted to go and what Lockheed Martin was looking for fit extremely well.
It is too early to talk about what I will be doing, but if it works the way I think it should, it could have some very big results and may have an impact on everyone someday. I can tell you it is a very different world inside of a big company - there is still a requirement to be entrepreneurial and sell the ideas, but once a big company like this gets behind it, the resources available are simply amazing.
More to come for sure...
by David A. Smith (noreply@blogger.com) at May 01, 2010 02:26 PM
Вот и вышла долгожданная первая версия методического пособия по текущей версии Крестьянство SDK, состоящая из описаний, рекоммендаций и документации. Скачать в формате (pdf) можно здесь: Методическое пособие
The first version of Krestianstvo SDK documentation book (on Russian) has gone online. Download is available in pdf here.
by Suslov Nikolay (noreply@blogger.com) at April 29, 2010 08:43 PM
Experimental Stereo 3D anaglyph filter for Open Cobalt.
To try, just load Cobalt-Stereo package into the recent Cobalt image from the contributions repository. To view filter menu item in the View bar, load or take the changes from the CobaltUI-sn.200.mcz
by Suslov Nikolay (noreply@blogger.com) at April 14, 2010 10:44 AM
I just bought a new phone, and it wasn't an iPhone, but it is still very cool. I have been planning to buy an iPhone as my next communication device - all my friends have one. I am very glad that they no longer feel the urge to demonstrate how cool they are by showing me some stupid picture or new app on their iPhone - except for Frank, of course.
So why didn't I buy an iPhone? Well, it is a bit complicated. My family has five phones with Sprint. I actually had a Rumor, which is a pretty good texting phone, but not much use for anything else. I was reasonably happy with it, though the blue-tooth quality was pretty poor. It was not too useful in California - unless you are married to the governator. Sprint is pretty good for quality of reception, but I always thought the selections of their phones sucked. A few years ago, I decided I needed a Blackberry and tried to upgrade at Sprint. Believe it or not, they would not sell me one. They only sold them to businesses. Morons. I did buy a Blackberry from someone else and carried two phones. I dropped the Blackberry after a while, because I realized I could almost always check my email with my MacBook, even when I was traveling.
So why the new phone? Somehow, I must have either dropped or stepped on my Rumor. I had made two or three phone calls earlier in the day from my office. I put it in my pocket and went downstairs to talk to my wife and while I was talking to her I received another call. I took the phone out and pressed the answer button and then saw that it had a big crack in the center of the screen. Worse, the voice quality on the other end was totally garbled - like some sort of electronica convolution filter. It was basically toast. I needed my phone to work this week, as there are many things going on in my life (that I will be writing about soon) so whether I liked it or not, I had to go visit the Sprint store for a replacement.
When I got there I had a few nice surprises - first the selections of phones was not terrible. In fact it was getting interesting. No iPhone of course - this wasn't AT&T, but they had an Android phone and yes, they finally were offering Blackberries to real people, and a they had the new Palm WebOS-based phones. I was interested in the Google phone, but a friend of mine had just bought one and was trying to take some pictures in the bright sunlight. The screen was unusable. Also it was kind of big and bulky - sort of like what the old Soviet Union might build if they were trying to make an iPhone knock-off.
What really caught my eye was the Palm Pixi. It is the smaller and slightly cheaper brother to the Palm Pre (which had the very strange commercials last year). I like small phones, as I already carry too much hardware in my pockets. The Pixi was actually smaller than my old Rumor (which really wasn't that small) and it was a real smart phone. Better yet, Sprint was offering a hell of a data plan where my family's monthly costs, which did not include data, would actually drop with the new plan which did include it. The phone was $200 with a $100 rebate - including a new two year contract, but now, even that was pro-rated. Sprint is definitely getting aggressive.
So now the review of the Pixi. In a nutshell, it is terrific.
Here is a list of pros followed by cons:
Pros - Setup was trivial. The guy at the Sprint store did most of the work and I had a working phone with all my contact info when I walked out. - The phone perfectly integrates with Gmail, which is my main email connection these days. It pulled all of my contact info into the phone and I was immediately reading the most recent emails. - It supports Google Calendar, which my wife and I share. And it issued calendar alerts. Very nice. - It is quite small, but the built in thumb-keyboard is quite usable. It took a little getting used to, but it works fine and has a nicer feel than my Blackberry or my earlier RIM device. I do love the size - it is quite thin and feels very nice in my hands. - Sprint's wireless network performance is great. I was at a Starbuck's with a friend of mine and wanted to show him a video I had posted to YouTube. He tried to access it with his iPhone, but I had it running on the Pixi well before he even had an connection. He never did get it to work, but he was using the AT&T network and not the local Wi-Fi. - Web browsing works pretty good, given the size of the screen. Certain sites, like Boing Boing are excellent, because they have a mobile version automatically loaded. Amazon was a bit crappy, surprisingly.
Cons - The text is too small, especially for us old guys. - The sound volume is not quite loud enough, even with it maxed out. - When I called my mother, she said the sound quality on her end was echo-y, like I was far away from the phone. - I tried to read a PDF document using the included Adobe reader app, but it didn't word wrap, so this was basically a lost cause. Seriously - if I zoom into a document using PDF, you really need to provide an option to wrap the text so I don't have to scroll left and right. - Camera quality is poor. Good enough for a random picture now and then, but it won't replace my Casio Exilim. - Takes a long time to charge (maybe 4-5 hours?) - Charge lasts about 3 days with use. Since it was a new phone, I probably did more with it than I normally will in the future, so this probably caused the battery to drain quickly. - Some apps re-orient based on the orientation of the phone. Others don't. - It really needs a search app that has instant access.
Overall, this is a great non-Android Google phone. It is really nice how cleanly and easily it interfaces with my Google life. And I love the size. It is really quite elegant. It has only been three days now, so let's see how it holds up over the next few months.
As an aside, I had a rental car last week - a Ford Flex. This included the Microsoft Sync software. I might comment more on this later, but short answer - it was terrible. I actually liked the car (more of an SUV actually), but this software was really opaque. After linking it to my now sadly demised phone via BlueTooth I could not figure out how to get to the phone interface to make a call. I nearly had an accident trying to figure this thing out. I never did figure out how to use the built-in GPS for directions. Luckily I had my Garmin Nuvi with me. Sync is Bad Bad Bad. If anyone from Ford is reading this - I did like the Flex, but will never buy anything with Sync installed.
by David A. Smith (noreply@blogger.com) at February 05, 2010 05:36 AM
For those who have not tried out the new Collaborative Curved Space Explorer in Krestianstvo SDK yet, here is the video which was recorded at Vologda State Technical University (Russia) during the "Virtual museum of geometry" opening event:
Данное видео с открытия "Интерактивного виртуального музея различных геометрий пространства" показывает работу многопользовательского исследователя искривленных пространств.
Tamarin-central, the stable source tree of open source VM used by
Adobe Flash, was
updated last December (Dec 22 2009) after relatively long
blank. The newer tree has faster VM and includes updated ABC
assembler and disassembler. Especially those ABC utilities are quite
useful to a binary hacker of AVM2.
Download latest Flex SDK
I found that neither Flex SDK 3.5 nor 4.0 stable build can compile
abcdump. You need to download later version from the Download
Flex site. Flex 4-Beta 2 (4.0.0.10485) works well. I would set the
Flex directory to environment variable FLEX.
Building procedure is well documented in Tamarin_Build_Documentation. Only
my additional suggestion is to add --enable-debugger, it makes error
messages easy to read, it helps you, really.
$ hg clone http://hg.mozilla.org/tamarin-central/
$ cd tamarin-central
$ mkdir objdir-release
$ cd objdir-release
$ python ../configure.py --enable-shell --enable-debugger
$ make
$ ./shell/avmshell -Dversion
shell 1.5 release-debugger build cyclone
features AVMSYSTEM_32BIT; ...
Build abcdump
There are various useful utilities in utils/ directory. Some utilizes
are written in ActionScript, so you need to compile them to
use. Abcdump, ABC disassembler, is one of such utilities.
core/builtin.abc and shell/shell_toplevel.abc are basic libraries
provided by tamarin, you can use them to try to see how abcdump
works. Note that you need to separate abc file names with --,
otherwise arguments are processed by avmshell instead of abcdump.
Abcasm is a ABC assembler. It is written in java and shell script, so
you don't need to compile to try it. utils/abcasm/test/ directory
includes various interesting sample programs. You can test them easily
and quickly.
$ cd utils/abcasm/
$ ./abcasm.sh test/hello.abs
test/hello.abs
$ ../../objdir-release/shell/avmshell test/hello.abc
Hello, world
by Takashi (noreply@blogger.com) at January 29, 2010 09:58 PM
Many people still have not seen the innovative display of the OLPC project's "XO" laptop. It has twice the resolution of a regular LCD (200 dpi), and works in bright daylight in gray-scale reflective mode. It's impossible for me to increase your screen's resolution by software, and I cannot make your display reflective, but here is an interactive simulation of the backlight mode with its interesting color pattern. This pattern is the source of a lot of confusion about the "color resolution" of the display. The LCD has 1200x900 square pixels, but the backlight puts a full color through each pixel. It is not made of red, green, and blue sub-pixels like a regular LCD, but the first pixel is full red, the second green, the third blue, and so on. The DCON chip (Display CONtroller) selects the color components from the full-color frame buffer.
My simulation of the DCON achieves the same effect by selecting either the red, green, or blue color component in each pixel. Just move the mouse pointer around to see how different colors are reproduced. You'll notice strong diagonal patterns, but remember, on the actual display the pixels are only half as large. Note that the actual DCON optionally applies a bit of anti-aliasing in hardware which is not simulated here. It helps reproducing fine structures and depicts colors more accurately. Additionally, the simulation shows a magnified image to better illustrate the principle, but it is not accurate because the reflective area of each pixel is not depicted. Maybe I can add this in a later version.
I made the simulation using Squeak / Etoys, which is one of the programming environments on the OLPC machine, but also works on Windows, Mac OS X, Linux, and many more systems. If you run the simulation on the actual laptop (download the project, place it in /home/olpc/.sugar/default/etoys/MyEtoys, run Etoys, choose Load Project), then you should close the small simulated screen and just leave the magnified view open.
For the interactive simulation, download Squeak (this version installs both, a regular application and a browser plugin), then click here to run the simulation in your browser, or download the project file, launch Squeak, and drop the project into it. Intel-Mac users beware, the plugin is not supported directly yet. To see the project in Safari, you have to quit Safari, set it to open in Rosetta (select Safari in the finder, press Cmd-i), and reopen. Or, use the download method, Squeak itself is running fine on Intel Mac, it's just the browser plugin that's making problems.
by Bert (noreply@blogger.com) at January 27, 2010 03:37 PM
I brought my green machine home this weekend, and my twins had fun with it. Enormous fun in fact for the two 7-year olds, pounding on TamTam furiously. I couldn't bear it anymore after half an hour or so.
Instead, I showed Jakob how to make a little figure bounce around on the screen in Etoys, while his sister went to practice her cello. He painted a simple head, and then we used the "forward by" and "bounce" tiles in a tiny two-line script making it move around. I made the mistake of pointing out that the "bounce" tile can produce some noise when bouncing. Endless fun trying the different noises ensued. Oh well.
Disturbed in her practice by these noises, Sophie came over and wanted to paint, too. So we saved Jakob's project and started a new one for her. I sat back to work on my email and let her brother teach. She spend like half an hour just painting the figure. The paint tool showed that it is not tuned to the XO's display resolution yet, it's far too small. But not giving up that easily, Sophie was erasing and repainting it over and over until she was satisfied with her "cow girl". Then Jakob proudly told her how to let it move and bounce, he had rembered almost everything needed. Together they quickly made it work, and just started exploring the noise-making possibilities again when we were saved by the call to dinner ...
by Bert (noreply@blogger.com) at January 27, 2010 03:37 PM
I gave a talk about the $100-laptop at the Magdeburg school of Industrial Design. We did some very inspiring projects using Squeak, Etoys, and Croquet together before. The designers always come up with interesting ideas, even though not everything is directly implementable by us developers.
Carola Zwick, dean of the school, wrote a book Designing for Small Screens that certainly gives valuable insight for OLPC developers, and she provided (though indirectly) some very important infrastructure for the OLPC office: her group designed the chairs they are sitting on. I got the actual invitation by Christine Strothotte, who got her PhD doing computer graphics in Smalltalk just a few years before I got mine from the same school. She's teaching interaction design nowadays. I'm looking forward to doing an OLPC-related project with these great folks.
A student took some photographs during the talk. Also, from his blog post it seems I convinced him of the merits of the OLPC project (it was a lively discussion). Thanks for posting, Cheng!
by Bert (noreply@blogger.com) at January 27, 2010 03:37 PM
I just installed Sophie on my green machine. Sophie is a project of the Institute for the Future of the Book, is implemented in Squeak (just like my Etoys activity on the laptop) using Tweak as its UI framework (which is the original topic of my blog). Tweak is also the base for the next-gen Etoys.
Installation went pretty smooth. I downloaded the cross-platform zip file using the Web activity from Sugar and unpacked it using the command line. The first start of Sophie failed, but after replacing the failing plugin with one from the pre-installed Squeak it started and worked. Yay!
This is an excellent example why it's a good idea to have a regular X11 installation on the kid's laptop: a lot of software will just work, even if it is not correctly integrated into the Sugar UI.
Michael Rüger of impara (a Squeak shop leading Sophie development here in Magdeburg, Germany) came over and made a little book, downloading two logos directly from the web (Sophie can do that!), adding a bit of text and color ... Tweak performance is not exactly blazing on the XO machine, I think we made the right decision to not use the Tweak-based Etoys but stick to the proven Morphic-based one. Of course one could optimize it a lot, but who has time for that? Anyway, it was useable - click the image to get a larger view:
by Bert (noreply@blogger.com) at January 27, 2010 03:37 PM
Lately I work on Squeak integration in the One Laptop Per Child (OLPC) project, perhaps better known as the "$100 laptop". The whole etoys group came over to OLPC's office in Cambridge. Squeak looks surprisingly well on the display prototype, and also etoys are reasonably fast. Ian Piumarta took some nice pictures, which might very well be the first photos of the actual display in the wild.
by Bert (noreply@blogger.com) at January 27, 2010 03:37 PM
For high-quality prints you need high-quality screenshots. This means very high resolution, and nice anti-aliasing. Just grabbing the screen produces rather unpleasant results (screenshot, 80 KB, 800x600 pixels). With normal OpenGL rendering you get rarely more than screen resolution, and anti-aliasing quality very much depends on your graphics board. So what to do?
Tiled Rendering comes to the rescue. Instead of rendering the whole image at once, we render smaller portions of the scene, and then arrange the tiles into a large picture. However, just pointing the camera at each tile will not work as intended, the perspective would change from tile to tile. What is needed instead is to construct partial viewing frustums that together exactly recreate the whole frustum. This sounds like a lot of math, but actually it is quite simple:
gluPerspective: fov aspect: aspect zNear: near zFar: far tile: rect | cotangent radians w h | radians := (fov/2.0) degreesToRadians. cotangent := radians cos / radians sin. h := near / cotangent. w := h * aspect. self glFrustum(rect left*w, rect right*w, rect bottom*h, rect top*h, near, far).
So I just extended the existing gluPerspective:aspect:zNear:zFar: method with a tile argument that gives the sub-rectangle in the viewing plane, where the whole picture ranges from -1 to 1. The only problem is to hand down that extra argument into the method. I ended up copying all the methods in the call chain, adding a tile: parameter. With the methods in place and a utility method to construct the right sub-rectangles, I could render the image from the first screenshot again:
| m c f | m := CroquetGlobals theTeapotMorph. c := m activeCamera. f := c root snapShot: m ogl camera: c tiled: 12. f := f magnify: f boundingBox by: 0.5 smoothing: 4. JPEGReadWriter2 putForm: f quality: 90 progressiveJPEG: false onFileNamed: 'croquet-bf-4800.jpg'.
Instead of 800x600, this renders 12x12 tiles, creating a 9600x7200 pixels image. The result is scaled down with smoothing to yield an anti-aliased 4800x3600 image, finally compressing as JPEG gives a 1.5 MB hires screenshot.
Beauty, eh? Never noticed that guy on the bridge before ;-)
by Bert (noreply@blogger.com) at January 04, 2010 09:11 PM
Milan just started a blog describing how to write activities in Squeak, see his first post. There are already a few of these, most notably the games by Robert Hirschfeld's students at the University of Potsdam, Germany. But so far the process is only documented in mailing list posts. Way to go, Milan!
by Bert (noreply@blogger.com) at January 04, 2010 12:36 PM
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