Useless things

Webtorrent; we get signal.

Lately I have been looking into WebRTC which is an open standard for real time communication between browsers. It allows communication styles in the browser which previously were not possible.

WebTorrent uses WebRTC for a protocol similar to bittorrent. Instead of having to download a program or install a browser plugin, you can download a webtorrent (which currently must be seeded as a webtorrent, by forexample instant.io) directly in the browser.

To test Webtorrent, I made a small javascript project. WT-widgets, is a collection of graphics for starting webtorrent downloads and showing download progress. Below is an example where you can download Artifact for Mac OS X using webtorrent.

No seeds

If there are no seeds, you can seed the file yourself by visiting the differently styled button below. This button uses a feature of WT-widgets that does a fallback to XMLHttpRequest after 5 seconds. When it is finished downloading the file, it will start seeding. Then the first button should work, since there is a seed.

The file will be downloaded in your browser, and you can then copy it to your filesystem by clicking the link that appears when the file finished downloading. This does not follow the usual download flow, so one of the aims of WT-widgets is to ensure that it clear to the user that a download is happening. I am not sure how well my widgets succeed in that regard, as my current widgets might not be the best at communicating that there is a download happening.

Suggestions or pull requests with fixes/additions are always welcome. I hope to expand WT-widgets with some widgets that show progress horizontally, as well as some widgets that more clearly show when it is in the different states of a download.

What Webtorrent sorely needs

While seeding in the browser works great, I do not want to have a browser fired up at all times to ensure there are seeds for my content. The best option I found for seeding webtorrents was webtorrent-hybrid, but when I tried it, I sadly could not get it to build.

Once Webtorrent has a solid solution for server side bootstrap seeding, I think it is will become a great alternative for distributing some kinds of content.

Take off every ‘ZIG’!!

Artifact 1.0.2.1 – Fixing OS X level 10+ crash

For some reason Artifact-1.0.2 would crash on level 10+ on some OS X installations. This seems to stem from some issue with my LWJGL version, the bundled JVM and those OS X installations.

Artifact-1.0.2.1 includes a later JVM which seems to work in my tests. If you experience any issues with it please report using the address here.

Download Artifact-1.0.2.1 for Mac OS X

Scape – a very ninja scripting language

I made a small scripting language that runs in the browser. It is very ninja. To see the ninja, first open Javascript console and write:

function recur() {recur()};recur();

Hopefully it blew the stack. Then type this into the Scape REPL:

def recur() recur(); recur();

When you are convinced it will infinitely loop without blowing the stack, hit ctrl-c to stop further processing.

Rincewinds rave, that is black magic! Also called tail call elimination. Scape code is not evaluated by snarfing functions from Javascript (JS functions do not have tail call elimination before ECMAScript 6), but instead is compiled to its own set of instructions, which are then run on a stack machine (running in the Javascript VM). During parsing Scape functions are checked for whether they can use tail call elimination. If they can, they get different instructions that reuse the existing stack frame.

More magic

Scape has forward mode automatic differentiation as a language feature. Automatic differentiation allows you to compute the derivative of a function, without having to define the derivative explicitly.

Without automatic differentiation, this would be the way to compute the partial derivative of the function $f(x,y) = x^{2}y^{2}$ for $x$ and $y$ :

def fun(x,y) * (* x x) (* y y);
def diff_fun(x,y) [* (* 2 x) (* y y),* (* 2 y) (* x x)];
diff_fun(4,5);
[200, 160]

With automatic differentiation in Scape, this is how it is done:

def fun(x,y) * (* x x) (* y y);
diff(fun(4,5));
[200, 160]

This is very useful for a number of numerical methods involving derivatives. The feature is currently experimental, it might interact with non-double types in funky ways.

Wai?

Mostly just for fun. I also started toying with the idea to make a safe scripting language for use in networked games. A language and runtime that would allow the player to define custom logic during gameplay without being able to ruin the experience for other players.

A dream would be a personalized Starcraft where it is you and your custom control scripts versus the other player and his scripts.

I hope to create a simple real time multiplayer game to show how I imagine it working. For now, playing with the Scape REPL is the only way to try the language.

Sayōnara

The “The question is dumb” checkbox is missing

Normally I do not answer telephone based marketing or marketing research, I try to answer polls though, since I think that spreading my opinion even if it ends up as one hundredth of one percent in a final statistic is slightly useful. What is critical for my participation in such polls though, is that I feel that my opinion is actually represented. Lately I have participated in several polls where the poll is fundamentally flawed and would lead to misleading statistics.

Last night I was asked if I wanted to participate in a poll on politics. Since there was no marketing questions mixed in I said ok. The initial questions were quite normal ones, like “which party did you vote for …”, “which party would you vote for …” and so on.

After a while the questions deteriorated, I do not remember all of them, but one that had me quire frustrated was this:

“Do you think the norwegian government should hire private companies for public tasks?”

To me this question is a a case by case question, there is no single right answer for the different activities a government might undertake. Now the poll does not allow this answer though, it only allows “I do not know” or strong or weak versions of “agree” or “disagree”.

In another poll on an earlier occasion, I was asked:

“Do you think syntethic estrogen is more damaging for aquatic life compared to natural estrogen?”

This question was extremely confusing to me. First of all I do not know if there is a difference between syntethic and natural estrogen (or what is meant by syntethic or natural in the question), secondly the only honest and respectable answer I could give is: “Whatever is the current scientific consensus”. The poll instead has me rating how much I agree or disagree.

I really wonder what the statistics derived from these questions were used for. Which dimwit made a decision based on the “knowlege” gained from it.

I could rant about this all day, but In my opinion rants alone are not good, it is better to propose a solution. What I think would make these polls much better is if there always was a “The question is dumb” checkbox, which had to be included by law, and which also had to be included in the final statistic by law. This way no ones voice is completely misrepresented as mine probably was in these cases.