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PythonMonk – Learn Python in the browser (pythonmonk.com)
162 points by akshat on Apr 4, 2013 | hide | past | web | favorite | 47 comments

Interesting, however I feel like learning to code in a browser (even if it's JavaScript) doesn't work.

Sure, you may learn how to do a for loop or how variables work. But, you don't learn how to actually use the language. Setting up a development environment, and understanding how everything is connected is much more important.

Let's say you ace everything here, on CodeAcademy, etc. You still can't actually build anything.

(For more on this, see this article from HN a few days ago: http://blog.zackshapiro.com/want-to-learn-to-code-start-here)

this kind of thing is a good resource for people who already know how to code, but need a fast and elegant syntax guide. its not useful for teaching beginners because, as you've said, it doesn't deal with the tool chain or project organization, etc. but if you know Ruby and want to learn Python, this is a great resource.

Agreed. I'm actually learning Python at the moment (coming from Ruby & Java), and am finding this useful. Generally I don't think too highly of coding in a browser.

The next step would be an ipython notebook verses showing the student the debugger console with prepopulated state in Javascript.. In fact, later lessons as modules to interact with in a notebook would be kind of cool.

I really don't buy the "you have to own a car to drive one arguments" and the whole point of modern software engineering is to pull you away from the assumption of full system control and the ability to make problems go away with shell skills.

But, I would like more immediate source code management integration. That is the essential reality I always see lacking..

A non-programmer that understood git basics would be more helpful to me as a colleague than a competent programmer that doesn't.

I tend to disagree. It works in a sense that it can take a person with no knowledge of the syntax and flow of a language and remove some of the fear of getting started. I think it is a great non-intimidating way to get an overview of a language. Yes, they are going to need more instruction, but it's a start.

We're building our way up to this. For now, we are focussing on helping more people teach how to think in a particular language.

We'll get to the rest fairly quickly, though that would likely be in the form of screencasts.

PS: I'm on the CodeMonk team, the folks that are behind PythonMonk.com and RubyMonk.com

The first thing I always try on sites like these is stuff like this:

__import__('commands').getstatusoutput('ls /')


__import__('subprocess').call(["ls", "-l"])

which gets blocked by the interpreter somehow with

exceptions.OSError - [Errno 11] Resource temporarily unavailable

I'm curious as to how you managed to do this - I've always been interested in how to sandbox something like this.

My very favorite Python sandboxing method is the one used by repl.it:


They compiled CPython with Emscripten, and it gets run on your browser.

This particular behaviour can occur because the process is disallowed to call fork() and can be done with setrlimit() (see RLIMIT_NPROC). There should be other protections, though, because forking a "ls" is not the only way to access the filesystem.

Ah, interesting.

File system access isn't blocked completely:



Execv'ing processes is OK as long as you don't fork:

    __import__("os").execv("/usr/bin/uname", ["uname", "-a"])
    Linux ip-10-196-3-111 2.6.32-amazon-xen-r3 #1 SMP Mon Jan 16 21:03:16 PST 2012 i686 GNU/Linux
As for the actual files, there are a few clues that a chroot is created for every request : /proc is not mounted, /etc is minimal (root + 1 user in passwd) and "ls -id /" returns a new inode number every time.

Yeah, we are using chroot (along with other things) to sandbox things on a per request basis.

- Tejas from Team PythonMonk (I built the sandboxing stuff)

__import__("os").execv("/usr/bin/env", ["env"])

Gives you a few clues as well

adam.py... :) If only I knew more about bytecode...

  import inspect
  import pprint
  pp = pprint.PrettyPrinter(depth=6)
  f = inspect.currentframe()
  c = 0
  while f is not None:
      c += 1
      if c == 20:
          print f.f_code
      f = f.f_back

This is beautiful and the usability is great. But can anyone recommend some online interactive Python learning that starts at the intermediate level? I need Pai Mei to whip my sorry skills into shape, starting with OOP, sockets, image handling, and maybe data persistence?

We already support teaching most of these - if you know anyone that would like to create courseware around any of these topics please let us know.

Our courseware marketplace is still in a private alpha, but we are actively soliciting awesome hackers that would like to teach online.

"Your turn now - go on and change the following code to compute the sum of the numbers 1 through 5."

If you input 15 and submit, it says the answer is correct. Do all online code courses just check for the retured value?

How do these services deal with someone running sum(i for i in xrange(1000000000000000000))?

But of course that is a valid piece of code!

"15" completely matches the specification you give.

Tried the test to define unique. Wrote

   def unique(s):
       return list(set(s))
and it gave assertion errors. Nice presentation ... but incorrect Python implementation.

maybe you had a typo? or they have corrected this in the meantime? I just tried this problem and it was error free.

def unique(values): """Finds all unique elements of a list.

        >>> unique([])
        >>> unique([1, 2, 1])
        [1, 2]
        >>> unique([1, 2, 1, 3, 4, 2])
        [1, 2, 3, 4]
    # your code here
    return list(set(values))

it also works without the coercion to list. return set(values) is fine.

Thanks for pointing the mistake. Corrected the tests now.

Solution to that problem is correct. Sets weren't introduced yet.

Both GitHub and Google signins failed for me and I lost progress in the first section. May just be the work network; I'll try it at home.

Seems like there is a bug over here http://pythonmonk.com/learning/books/17-python-primer/chapte...

"Evaluates to True when age is 40 and name is "Bob" , which should be fine i think.

I think this is a great way to get beginners / students coding, but the end product might be what we now know as "bolt-on" engineers. They put components together and build beautiful functional products, until it breaks and they have no idea what's "under the hood"

This is really cool. I think the assertions that this learn-in-the-browser thing doesn't work is because folks on HN have seen so many entry-level courses at this point.

More interestingly, can I get transfer credits from Codecademy instead?

Looks like it sends each command to run on a server - I'm curious why not execute it in the browser? (There are a few solutions for that?)

I tried llvm based project https://github.com/kracekumar/test-empythoned(empythoned: https://github.com/replit/empythoned). There are few limitation I am facing, `import` system don't work(compilation issue). From my experience more effort is required.

It is 2013. Why are you teaching Python 2?

"A programmer may try to get you to install Python 3 and learn that. You should tell them, 'When all of the python code on your computer is Python 3, then I'll try to learn it.' That should keep them busy for about 10 years."

- Zed Shaw, "Learn Python the Hard Way"

while I agree that we should be more proactive about migrating to Python 3, if you're trying to be pragmatic it is most useful to teach Python 2.7 since that is the most widely used version.

Python 3, in 2013, is not lacking in pragmatism. It's not new, or experimental. Someone just learning today is going to have to immediately turn around and relearn things because they started out with an old version.

Clearly you are not a python developer. This isn't correct at all. First, there is nearly nothing to relearn if you target 2.7.


Second, most software of any complexity will have dependencies. Although progress has been made, several packages that many projects depend upon are still red:


I'm teach Python professionally. People come to learn Python so that they can go back and use it at their work place. And almost all Python installations in productions are in Python 2. I'm sure it is going to change soon once Linux distributions make Python 3 their default version.

P.S. I'm the author of Python Primer on pythonmonk.com

I don't know anyone who uses Python 3 in production. It's still seen as an experimental implementation.

In Arch linux python 3 is default, https://www.archlinux.org/news/python-is-now-python-3/

I've seen more installs of pypy in production than python3.

Not experimental, just that there are good libraries that aren't Py3k yet.

I dont' know Python but I'm thinking about learning it. What's experimental about Python 3? I don't have any legacy reasons to start with 2.7. Why wouldn't I just start with 3?

there's nothing experimental about Python 3. its a stable release version and I think its already up to sub version 3.3.

HOWEVER, there are many important 3rd party libraries that have not yet been migrated to be fully compatible with Python 3. these libraries are far more important to writing real applications than the ability to use some newer syntactic constructs in Python 3.

> HOWEVER, there are many important 3rd party libraries that have not yet been migrated to be fully compatible with Python 3.

Are there any particular libraries blocking you? Numpy / SciPy, IPython, Requests, Django, Pyramid, Bottle, etc. have all been ported to Python 3.

South (database migration for django). Until django core has its own migration tool I won't be using it with Python 3.

PIL as well. similar reasons. django image fields are dependent on PIL.

Celery is still on Python 2 also, and while there are other message queues available, none of them is as easy to integrate with for an app that's already written in Python.

To replace PIL you should try Pillow, a fork of PIL that is capable of running on py3k (and 2.x).

The Python 3 Wall of Superpowers / Shame lists them for you in order of downloads: http://python3wos.appspot.com/

To be fair, Django only supports Python 3 as of 1.5, which was released a bit more than a month ago.

"immediately"? Try again in two-three years, if that.

Very far away from Perl Monks.

This probably isn't for experienced developers, but it looks gorgeous.

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