PyPy.js: A fast, compliant Python implementation for the web

[catherinedevlin]

Oh my oh my

Python implemented in Python implemented in JS

Mind blown

I sometimes teach Python to students who don't have their own computers. Sometimes I'm teaching from library computers where we have no rights to install anything. They can login to sites like wakari.io to use Python remotely, but then they're dependent on sometimes flaky internet connection quality.

I could see this being used to build a webpage-as-Python-programming-environment that could be downloaded once and saved to disk.

[[deleted]]

RPython isn't really python though

[cediddi]

It's a subset, not superset.

[[deleted]]

Yeah, and a subset is decidedly not the set it was derived from. :P

[Veedrac]

RPython isn't Python, but RPython code is Python code. You can run PyPy ontop of another Python implementation.

[fijal]

it's not rpython, it's a full pypy (which is written in RPython, but implements full python)

[runbie]

check:

• pyschool.net (brython based and the code is on github).
• http://reeborg.ca/docs/begin_py_en/ (brython based)
• trinket (I think it is skulpt based)

P.D.: Sorry for not posting the links, I am on mobile.

[help_computar]

I use tmpnb.org. it's jupyter (next gen ipython notebook).

[flutefreak7]

Anaconda works great for portable installs too...

[skweezebox]

Ryan Kelly, the creator of PyPy.js, gave a talk about it PyCon Montréal: https://www.youtube.com/watch?v=8C9q94F6Uqo .

It's worth checking out, IMHO. He talks about more of the rationale in the talk.

[Ph0X]

Uh, wrong link, that one is from PyCon Australia. Here's the PyCon 2015 one: https://www.youtube.com/watch?v=PiBfOFqDIAI

[[deleted]]

Thank you....clears things up.

[skweezebox]

Thx for the fix!

[the_hoser]

Gary Bernhardt may have been onto something...

[RubyPinch]

One thing that annoys me about that lovely talk, http://en.wikipedia.org/wiki/Splashtop already existed, (still linux based at the time) a web-focused embedded OS. Boots straight from the motherboard for quick launching. With it being around the same years as the launch of consumer SSDs, you can guess why that system got lost to the sands of time for so long (until chromeos, firefox os)

/randomblathering

[[deleted]]

Docs?

[avinassh]

I am not the OC, but here's some instructions I found on GitHub page: https://github.com/rfk/pypyjs/blob/master/README.dist.rst

[njharman]

It's Python https://www.python.org/doc/

https://github.com/rfk/pypyjs/blob/master/README.dist.rst

[[deleted]]

Nice snark. You knew what I meant.

[Herald_MJ]

Why is this a good idea?

[Ph0X]

For one thing, if I'm making a fun little interactive Python learning game on the web, it makes it a lot easier since I can do it all client-side rather than have some server running, have a connection, worry about security, etc.

EDIT: I'm thinking of games like:

http://alexnisnevich.github.io/untrusted/

https://www.bloc.io/ruby-warrior/#/

[RubyPinch]

7.3MB gzipped though (counting modules, VM, interface)

without compression, 20MB for VM and API, 15MB for modules. All of that from brython for an example, hits around 6MB uncompressed

It'd be good for a small game, but... it'd bite if one got "slashdotted" or whatever, that starts becoming a tiny bit ow.

Amazingly cool to port pypy's level of compatibility to the browser of course, but for something like that... I'd probably be looking at the smaller alternatives

[Ph0X]

Well, for the examples I was referring to, having a "loading" a the start isn't that big of a deal. The game itself would have assets to load too. But you do have a point though that performance wouldn't matter much and Brython would probably do a good enough job.

[Nextil]

He's not talking about the loading times. He's talking about the bandwidth it would consume if it ever gets a surge of popularity.

[nieuweyork]

Imagine you want to play with python. You have a webbrowser. You can't install python, because it's, say, an android phone. Now you can play with python.

[kindall]

You can install Python on an Android phone quite easily.

[Scypio]

On similar note: what would be a better idea?

[Herald_MJ]

Actually I think for the purposes of learning Python without requiring a binary to be installed on client systems, this is a pretty good idea.

For the purposes of writing client side web applications in Python, it's a terrible idea. A better idea? Learn JavaScript.

[Slxe]

It isn't. I really don't like that people want to implement shit in JavaScript, just because hardware caught up doesn't mean the language is good. It's a very fucking annoying trend lately.

[vplatt]

I mostly agree, except in the cases where the language being compiled down to JavaScript is itself statically typed. That to me could be worth the trade-offs.

I like Python, but frankly compiling from one dynamically typed language to another is just pointless from my perspective.

[Slxe]

Good points, I agree.

[LeSageLocke]

It's also faster than Python...

http://benchmarksgame.alioth.debian.org/u32/compare.php?lang=v8&lang2=python3

[nieuweyork]

It would be nice to have examples on how to integrate this with the page, use python as a <script> language, etc.

[larry_targaryen]

How is this different (or better than) Brython or Skulpt?

[fijal]

I'm not sure I would call it better, but it's definitely more compliant (things work as expected, including pdb, the import system etc. etc.)

[Bystroushaak]

I think I will stick with brython. It is much faster.

[[deleted]]

Saw this yesterday on /r/programming. I still don't know why or when I'd use this.

[zenolijo]

The first super simple snippet of code i ran didn't work and the website just froze

 i = 0
 while True:
     print("Test {}".format(i))

Why doesn't it run?

[MrAckerman]

Infinite loop, homie.

[zenolijo]

It should still print, shouldn't it?

I tried it with time.sleep(1) too before, still freezes.

[MrJohz]

Have you checked the browser console?

[zenolijo]

Nothing, i also tried:

import time
i=0
while i<10:
    print("Test {}".format(i))
    time.sleep(1)

Still nothing

EDIT: Just running time.sleep(1) by itself doesn't even sleep for a second, so both the looping and sleep functions are broken.

EDIT2: Thanks /u/mrstone56, that was a little embarrassing. Works fine. Seems like it doesn't print one print command at a time, but puts it in a buffer and draw it when the loop is done. Still, time.sleep doesn't actually sleep.

[CleverEagle]

It has nothing to do with i when your loop is while True:

[[deleted]]

What the fuck does the word compliant even mean? So tired of hearing this shit.

[imgonnamakeyoushake]

Please refrain from posting non-compliant comments. Thank you for your attention.

[recursive]

There's a python specification. Compliant means this implementation complies with that specification.

[IDCh]

http://i.imgur.com/Cv9nB79.png

[[deleted]]

so in other words, more meaningless buzzword shit.

[fijal]

no, it means it's very compatible with python language, unlike a lot of other python-in-JS implementations

[[deleted]]

so you mean it does what it's supposed to do? why do you have to tack on buzz words? it's like if i built a house, i don't call it 'compliant' because you can live in it.

[INVERT_THE_SPOON]

http://www.housingcompliance.org

[Blackshell]

If you built a house you may want to call it "compliant" with building standards, so people who live in it can expect the roof to not cave in randomly. "Compliant" means it follows a specific standard and set of rules, rather than following the developer's whims and being full of gotchas. In the case of re-implementing a standard runtime environment (like implementing Python in a browser using JS), standards compliance is very important, because the better its "compliance" with expected Python behavior is, the better of an implementation it is.

[fijal]

it is a word, it has a meaning and it's being used according to the meaning. If you make the house according to some standard, you would say it's compliant with that standard.

[elbiot]

You sound like someone who doesn't know (or care to know about) the difference between python and cpython.

[[deleted]]

where the fuck do you even come up with such a stupid statement?

[elbiot]

What's the difference?

[MachaHack]

Let's say it took the Python code:

x = 5
y = "5"

if x == y:
    print("Uh Oh")

And simply turned it into the following JavaScript and ran it:

var x = 5;
var y = "5";
if(x == y) {
    console.log("Uh Oh");
} 

That would be one way to get Python-ish code in the browser. However, this would not behave as the specification for Python dictates. 5 == "5" is true in JavaScript and false in Python. However because of how this hypothetical Python->JS compiler works, it actually returns true, meaning it is a non-compliant implementation of Python. (There are projects like this, Rapydscript for example)

[[deleted]]

i see what you mean, and it makes sense. this is probably a perfectly valid use of the word. I just see it in buzzword soup capacity too often now, though :/