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Monday, October 06, 2008

Inspy from Turtle Geometry

Turtle Geometry by Harold Abelson and Andrea diSessa has a lot of interesting examples of turtle graphics. Especially I was fascinated "inspy" program. The basic structure of inspy is same as spiral. But instead of the side, value of the angle is changed in each step. I have explored a bit for a demo of Chalkboard project

To make the study easier, I made a trick to connect an event handler and an inspy program. You can play with a dynamic version of inspy program with it (Please move the mouse on next rectangle). And you may find various patterns even from such simple program. Here I present stand alone version (Only Firefox and Safari are supported).

inspi = function(side, angle, inc) {
  for (var i = 0; i < 720; i++) {
    right(angle + inc * i)
inspi(15, mouseX(), mouseY())

Tuesday, September 23, 2008

Ostranenie - Crossover between Art and Programming

It looks like that I have to say something at a camp next week. So I trumped up the most easy topic for me, the art. For me, the art is very common and familiar thing that I spent a lot of time to discuss such matter in my youth. And more importantly, it is somewhat strange topic for colleagues. I hope it will be fun.

One of the most important functions in the art is ostranenie. Ostranenie is a term coined by Russian critic Shklovsky, which means looking a familiar things in unfamiliar ways to find a unexpected side of the subject. For example, most surprising thing for a student who learns a sketch first time was there are no outlines in the world. Young kids often draw an outline to express the mom's face. But reality is that a human brain extracts an outline from a contrast of of light and shade.

Also a programmer often faces ostranenie. A human tends to think based on an intuition. But a computer only obeys logics, it never cares about human's common sense or intuition. The conflict often cause errors. But the errors give us precious ideas that we have never noticed. Human beings have developed common sense and intuition through the long history and culture, so it is very difficult to perceive a difference between logic and intuition without a computer.

We can regard the invention of computer in philosophy as the invention of photograph in the history of art. The invention of photograph provided an artist first different eyes beside human's. And it brought Impressionism in 19th. Likewise, we met another kind of brain for the first time by computers. No one knows what is born from there because the history of computer is still young. But we can explore new directions in terms of ostranenie.

Thursday, September 11, 2008



Chalkboard is my latest web authorizing tool for active essay. I have just uploaded it here I tested both Firefox and Safari. I know there are still a lot of UI / technical issues though, I am sure that basic feature is enough for my purpose, and I will keep it simple.

My biggest concern at now is supporting Internet Explorer. I thought it was not so difficult for such a simple web application. But actually it was horrible! and I couldn't solve yet. I might go bad direction though, I was really disappointed about different behavior of layout. One can say that it is unnecessary to support various platforms for such an experimental project. But I think it is important because I hope it will get real users finally.

When I had to decide a name of directory for this project. I named it "chalkboard". I felt the spell was too long as a directory name, but I'm comfortable about this naming now.

Here are features.

The screen have three areas, editor, play area, and transcript. You can write text or source code on the editor. Any text is executed as a JavaScript program with [do it] or [print it] command. [do it] command prints the answer on the transcript, and [print it] shows the answer on the point of cursor. The play area provides a free space to user. It is used any purpose, for example, you can make a drawing tool to attach canvas element on it. See

The Chalkboard includes a bunch of pages. Each page consists text and source code. Sauce code is usually written on <pre> tag.

All source codes written on <pre> tag in a page are invoked with [run] from top to bottom. This is useful when you encounter unknown page, and want to try at first. <pre> tag is used when the project is called by includes function. See

You can make a new page to specify new name after hash mark of the URL like In this case, a page named NewPage will be made.

Here are some design decisions.

The editor allows only paragraph level editing. You can make a line become h1 (header 1), p (paragraph), or pre (program), but you cannot make a word become bold or italic. Link command is only exception case (you can make a word become a link). The reason is web browsers have different behavior on the editor component, and I don't want to support each corner case. Rather than that, decided to provide minimal set of features.

Chalkboard uses IFRAME + editorMode property for the rich text editor. There were another possibility. One is DIV + contentEditable, and another one is FRAMESET. Those were pros and cons. I use IFRAME simply because it was easiest way in Firefox and Safari to make available this layout configuration, but I might change my mind.

Tuesday, September 02, 2008

My personal history of Web Authorizing Tools (2)

Tinlizzie Wiki

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

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 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.

My personal history of Web Authorizing Tools (1)

I have been facinated by the idea of combining web authorizing and programming even before I realize it is called Active Essay. Actually I made a numbers of projects along with the idea. Here is a short story of my side.

Scamper Workspace

Scamper Workspace is a extention for Scamper, a web browser written in Squeak. It runs a Smalltalk code on any web page with simple operation.

I often write a tiny source code in Squeak on my blog. And it is natural that you want to run the code without any effort. Usually, you might have to copy and paste from web browser to Squeak. However, although Squeak has already a web browser named "Scamper", why do we need such clumsy way? What's wrong if a web page is just a text as same as other Squeak's text object, and if you can use full features which Squeak IDE has on it. Scamper has very limited as a web browser, but it is just O.K. to examine a code on blog. Only missing thing is a direct way to execute code on web page.

"No Application" is Squeak's original motto. Squeak consists with a number of objects that they have each different tiny functions, and those are connected naturally. In that sense, there are no need of "Application" because application is just an artificial boundary. So it seems to me natural to add Workspace menu into Scamper.

Because all necessary code is already available in Squeak image. The implementation was very easy. However the result was surprisingly attractive and profound. Thoru Yamamoto made a lot of contents for Scamper Workspace and each of them are so exciting.

Typical page written for Scamper Workspace consists with a short story and a couple of codes. A reader would executes the codes while reading a story. This format is very effective when the story is to explain how to make a graphical program in Squeak. Especially the fearure is emphasized when a page consists only text and source code. Even it lookes if it were 1995's website, it make large variety of effects if you run the code. I would say that it could be another possible evolution path for the Web.


StackWiki is a multimedia authorizing tool written in Squeak. Document is saved as original binary format with Swiki Server.

I made StackWiki inspired by Zest and Marmalade. Zest is WYSIWYG authoring tool like Wiki uses local disk, which allows you to make link to other page, and dynamic content in Smalltalk language. Above all, StackWiki emphasis more features in HyperCard and Wiki.

A StackWiki project consists with one or more pages. In WWW, nomally relationship between pages is maintained only hyper link, but there is no structure like hierarchy or order. Some websites attempt to show such structure with navigation link.

Structure among pages helps user to know a point within the context though, it often makes UI complicated. Addition to historical navigation, forward and backword navigation is needed if pages have an order. Above all, if there is hierarchy, three dimensional navigation would be necessary, In StackWiki, only foward and backword structure is used.

With background, you can put together similar structures in multiple place in one. StackWiki only allows one background, although HyperCard could handle more. Background is implemented as a special "background" page. If you add something onto background page, the element are shown same place behind other elements in all pages.

Here is another interesting trade off. How complicated background is needed? Background can be seen as a special version of macro. Macro is a generic term to represent common structure among document. Macro is very useful to reduce redundancy and to improve maintenance factor. However, it is easy to make too complicated macro which includes macro of macro. In end user's point of view, background can be better than full macro.

Each StackWiki's page is stored as a binary format in Swiki serer. Although, Swiki is itself web application, it is used just as file upload feature. StackWiki doesn't use any web standard except HTTP transport to save data. It doesn't so good attitude in terms of data transparency. But it makes the development so quick that it took only three days to implement it.

Monday, August 25, 2008

Active Essays on the Web

Active Essays is a concept of an essay mixed with computer program coined by Alan Kay. The goal is to explain mathematical or scientific ideas to kids with some interesting program like a computer simulation.

It is similar as a math book which includes a couple of paragraphs and formulas in a page, so that a reader would follow the author's idea by not only reading a text but also "do it" formulas. In case of Active Essays, computer programs are embedded in a page instead of formulas. The largest advantage of Active Essays to math book is that a program is often more dynamic than a formula. It is really fun to see a small lines of code generating a little surprise on screen. The second advantage would be that you don't have to calculate numbers by yourself, a computer must to do better job than you to fiddle variables.

Because Active Essay is not a definitive genre in computer media, so I'm not sure how many active essays have ever been written so far. But HyperCard might be the first media which affords contents mixed with text and program. And you would find many projects with this style in eToys on the web.

What I want to make in next a couple of months is an authoring tool for Active Essays taking advantage of Internet technology. And final goal is to describe entire system as a Active Essay itself.

Internet had a huge impact on our literacy. A lot of amateurs write texts, take photos, and publish to the web them every day. Even it is common that there are families whose every members have each blog. Besides social aspect, a new medium makes a new style of writing. Because actual appearance of writing is depended on reader's web browser or RSS reader, you don't have a full control of final looking of your text. And it is encouraged to take care about logical stricture instead of physical looking. I'm sure the those phenomena affects way of writing.

However, there is a something what have not been changed yet. Internet contents still tend to mimic traditional media. Even though it is highly depend on computer technology, it lacks the most interesting aspect, programming language as a communication media.

Programming language is the primary tool to talk between man and machine, and often even better way to exchange ideas among humans. If there were enough support tools, it would be natural that we write a blog post in programming language, chat with source code, and even write a novel running as a program. Especially when the topic is science or mathematics, programming language would be the most accurate way to tell an idea. It is irony that you can't play a LOGO program when you read LOGO's article on Wikipedia.

However, e.g. while the article on Logo has some good information and examples, none on them can be run, dynamically changed and tried, etc. To me this is outrageous given that the browser was done some years after Hypercard, longer after the Apple ][, and long long after the prior art of the 60s and 70s. -- Alan Kay

What kind of tool is useful to support the idea? Abundant introductory material for science written in eToys would be a good start to examine. And history of Literate Programming shows another interesting aspect of the topic. We would make a progress from these instances in terms of functionality and style.

As functionality, Don Knuth's original idea could evolve more in late binding language like JavaScript than Pascal or C, because WEB's some clumsy convention like macro is needed only for language's inflexibility. And as style, we can avoid limitation coming from physical paper. We don't have to care about pages nor font size, but let's concentrate its logical structure. Hyper link helps to support navigating in random access instead of page numbers.

This is an outline of current thought. I don't think special fancy feature is needed for first prototype (actually, I have made a lot of prototypes already, and this is not exactly the first). The simplest solution might be best. And when we need more, I would make everything from scratch in "Ian's System" later.

Sunday, August 17, 2008

My next three months goals.

The main point of my previous three months goals was making a text editor on Ian's stuff I admit that it has not been finished in terms of building a really useful text widget. Making a text editor looks simple requirement. But even just a substitute widget for Squeak's ParagraphEditor from scratch is quite complicated because it has to deal with a large number of issues like text layout, scroll, font rendering, etc. To make the goal clearer and smaller, I propose one concrete prototype and one real implementation.

An authoring tool for Active Essays on web browser.

It will be direct successor of TileScript and YUI-based tool for Active Essays Those were difficult to use even sometimes for myself because they were too heavy and UI was complicated. The focus of this project is brushing up the UI. I will not add a new function, but it will have enough features to express some of examples in Appendix A of STEP paper and Ted's puzzle.

  • Basic text emphasis (header, list, in-line image)
  • Wiki based collaboration mechanism.
  • "include" mechanism
  • OMeta/JS can be used through "include"
  • Supported platform: IE6 and Firefox3

A basic widget component for Active Essays on Ian's stuff.

This is a real stuff based on above prototype. Every necessary widget which needed for text editing including text emphasis and in-line image will be implemented. Wiki-based collaboration part won't be included.

This text widget can be used a part of Ted's DB Jr.

Next Goals of My Hobby

I need my next three month research goals by next Tuesday's meeting. But it is too hard for me to write a documentation before writing source code. Because I'm a 100% pure programmer, I program therefore I am.

But I have to write something anyway. It might be better to write something fun idea before serious documentation. So my brain will switch to "writing mode" smoothly. So I made up my next three month hobby goals. This is it.

Simple Electronics Device

When I was first interested in electronics was around ten years old. I have tried a couple of electronics projects. However, I had never understood how to decide parameters of component. Sure, resistors and ohm's law are pretty easy, but capacitor, transistor, coil, such components are quite difficult. I hate numbers and I am too lazy to handle complicated equation.

Those knowledge is completely unnecessary as a programmer. But same time, I couldn't tolerate the fact that I was ignorance about electronics. So I got started to learn it again a couple of month ago. First goal is to make a simple device to communicate between a computer and real world. This is one of early attempts.

FPGA Block RAM and Demonstration

I happen to get a source code of tiny CPU in Verilog. This is quite beautiful so I bought a Spartan-3A FPGA board for $200 to test this code. FPGA is very interesting gadget. But it requires different ways of thinking against programmer's view. So I still do nothing for it. One of the problems is I don't understand how to use Block RAM. And I don't have nice idea to demonstrate it. Just running a CPU is too boring. I wish I can run the verilog CPU with fun demo perfectly.

A Compiler in Javascript

It still doesn't go beyond a joke. I have played a tiny source code in x86 assembler with GNU as. It was when I was teen that I played Z80 CPU, and I was surprised the some essence of Z80 machine code is still alive in modern CPUs (I had imagined as if modern CPU might have hundreds and thousands of generic registers, but still we call EAX register as an accumulator!). I can't say as it is good though, it is very appealing to me.

So I think that it would be fun if I will make a compiler, assembler and linker in Javascript on a web browser. It might support only one CPU and one platform like x86 linux, still it should be a good exercises.

I could write those ideas more. But this is it today.

Saturday, August 16, 2008

Documentation and Programming Language

A number of major programming languages have its own documentation system. Those variations themselves interest me very much. I picked up some of them and examined.

There are some interesting points to characterize those systems.

  • Text base VS Memory base: A text based documentation system is implemented as just a text formatter. But some are integrated in the language itself, so you can access the documentation in run time. Emacs Lisp is a significant example of Memory based documentation. I think Memory based documentation is more useful though, sometimes Text base is handy because it doesn't need to load a program only for the documentation.
  • Description part and Reference part: A documentation might include a description part, which describes overall goals and functions of a part like a class or a module. In contrast with description part, a reference part describes detail of a particular entity like a function or a variable. A reference part is connected with its source code of definition.


Perl's documentation is described by POD (Plain Old Documentation). POD is a text based system. It has only description part.

POD is a very simple markup language and it has only enough mechanism to represent traditional UNIX manual style which includes certain sections like NAME, SYNOPSIS, DESCRIPTION, etc.

A POD document is embedded in a Perl program as a comment and the Perl's parser just ignores it. A POD parser just ignores program. POD doesn't use any information from the program source code.


JavaDoc is the standard documentation tool for Java. It is a text based and it has both description part and reference part.

JavaDoc parser uses not only comments but also program codes to extract type information and class hierarchy. Even it works if you don't write a comment. Very structured HTML documentation is generated by the tool.

Emacs Lisp

Emacs Lisp has memory based documentation. And it has only reference part.

Emacs Lisp's documentation is highly integrated with Emacs editor. You can access help document for every functions and variables without external tool.

A documentation is described as a first comment in a function or a variable definition. This comment is parsed by Emacs lisp parser, and shown by help command e.g. M-x describe-function. Help system of Emacs Lisp doesn't have description part, but info manual of Emacs lisp complements overall information.


Python has memory based and text based documentation. And it has description part and reference part.

Basically Python's documentation is same as Lisp's. A documentation is described as a first comment of an entity (module, class, variable, etc...), and parsed by Python parser. You can access the documentation through __doc__ property in run time.

I don't know much about Python. But Python is unique because there seems to be a way to extract documentation by text processing like Java and Perl. I'll learn about it later.

Squeak Smalltalk

Squeak Smalltalk doesn't have documentation system. It is not necessary because the IDE is strong enough. But you can see IDE itself as a memory based documentation system. Class comment is used as a description part, and method comment is used as a reference part. Class browser has mode to hide source code but comment.

Wednesday, August 13, 2008

What does documentation lose?

I realized that Knuth emphasized narrative way to express a program documentation instead of formal way in "Literate Programming" paper. The reason why WEB needed macro mechanism which Pascal didn't have was that it was needed to make the program flexible enough so that an author can keep order of original thinking flow on the text. Using WEB, whatever each symbol dependents on others, you can write down in any order which you like.

a program is, likewise, ready to comprehend it by learning its various parts in approximately the order in which it was written. -- LITERATE PROGRAMMING

Such consideration have been lost in current documentatin mechanisms like JavaDoc. Major goal of documentation generator for programming language is to make a comprehensive reference, certainly, literary value would be out of scope in those systems. I expect thet My Active Essays project would be a missing link following the lost feature.

However, before diving too deep, I need to know current art and science of program documentation... to be countinued.

Sunday, August 10, 2008

Things in my mind recently

A couple of people asked me about this blog, so I add a new post finally. Because I don't spent my major time for Squeak recently, I changed the title of it with more general flavor than "Squeak Everyday". But "Workspace" is still a keyword from Smalltalk. What I am doing everyday is still dynamic hacking with / without computer.

I'm quite interested in relationship among programming and documentation. It was 80' when Knuth wrote about literate programming In this article, he seems to be too excited about his idea that a program is a literature. How far we have elaborated the idea since then. Yes, from Emacs's documentation to JavaDoc, there are a lot of great works. But I'm not sure those are really literature, in other words, those are fun to read. In fact, although I am really fun of API documentation as a hacker, it could be more entertainment. That's what I am thinking these day.

When I was working on my old work (2007), such idea was in my mind, too. And I'm going to visit it again.

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