Brython - Python to Javascript translator

If someone makes a good looking website for his project it kind of gives the impression that he is seriously going for it, perhaps it is not good now, but maybe it will become a serious contender later.

There are many OPs that assert that JS syntax/lang are beautiful once you get handle of it, and may be it is...

However, there may be enough people like myself for whom the JS syntax/lang just do not fit into the brain. Since at my last job of CFO of $200+m pharma country org I have architected multidimensional db for an OLAP cube for SAP Business Objects, I do not think that I am that dumb. But this JS stuff just does not fit in.

Also, I do value my time. So although I could persist in learning JS, as a general rule when things do not flow - the learning time multiplies. I do not have time.

Hence, personally I would love to be able to write/maintain code in Python [even subset of Python would be fine], knowing that it cleanly compiles to JS. It will be then my choice whether I want it client-side or server-side [smth like what css pre-processors SASS/Less are doing].

Python doesn't specify the complexity of dicts, that they're "efficient" is a CPython implementation detail other runtimes happen to copy. Even a worse-than-linear time mapping that satisfies the protocol is still a 'dict'. Surprised you don't know this given your relationship to PyPy.

As for whether I'd prefer a 100kb "not quite Python" or sending a few MB of JS (that takes 10 minutes to translate for each change) to the browser just to handle a few functions in a cross-platform manner, I'm glad to see more options when making this choice.

I'm in the midst of evaluating a solution to running simple mathematical functions on a Python backend or in-browser (for graphing). In a case like this, a handful of crappy guarantees about the lowest common denominator arithmetic is all I need in a solution. It's easy to get wrapped up in correctness, but ease and practicality trumps it almost every time.

However if I was to implement a Python to JavaScript compiler, would there be some benefits in transforming the Python AST into a JS AST first?

There are existing code generators such as escodegen that transform that AST to JavaScript code.

In the end, it was hard to replicate 100% of the usefulness of JS through python and convert python's cool features into JS.

Because as cool as the project is (from a scientific perspective), ultimately it will end up not being used by anyone. Most developers and companies who build production grade software for a living stick to true and tried technologies, vs. fancy esoteric stuff like this.

Don't get me wrong, I am not knocking this project and the person who created it, I am just stating the obvious reason why things like this rarely take off.

https://github.com/jashkenas/coffee-script/wiki/List-of-lang...

For many of the offerings in the list, the problem, IMHO, is the lack of a complete story.

If you base it on an existing language - in this case, Python - you would expect a full implementation of the language, or at least a good portion of the core language features. The benefits of an existing language are often familiarity and the potential to reuse existing code. With partial implementation, you can hardly gain these. And the downside of extra abstraction quickly outweighs any superficial perception of familiarity.

If you create a new language, you have to strike a good balance between language features and interoperability. You need to bring enough new things to the table to make it worthwhile to learn, adopt and support it, and yet you can't overstate the importance of a good interoperability story unless you can afford to completely ignore the JavaScript ecosystem. See DART.

Much of the slowness was because emscripten was immature at the time that repl.it worked on their port. If someone built python with current-day emscripten it should be much faster.

There is a better way, though. We could compile PyPy's generated C implementation and add a JIT to JS to that. That would be the best way to get fast python into the browser. If anyone is interested to hack on that let me know, I would assist from the emscripten side.

Note though that this would only give throughput speed, not startup speed. For startup speed, a method like pyjamas or bython will do better - at the cost of not fully supporting the python language, of course.

Although, speed is way less important when the code is running on lots of browsers out there, compared with running lots of instances on your server.

"""Historically, designers and implementers of application protocols have often distinguished between standardized and unstandardized parameters by prefixing the names of unstandardized parameters with the string "X-" or similar constructs. In practice, that convention causes more problems than it solves. Therefore, this document deprecates the convention for newly defined parameters with textual (as opposed to numerical) names in application protocols.

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community."""

Based on your personal experience - with which one to start?

I don't think I would've implemented it this way, because:

1. It introduces the latency of having to download brython.js with every page load.

2. It supports only a subset of Python, whatever the implementor has gotten around to implementing. That's a pretty small subset so far - no list comprehensions, and I doubt he got the class & metaclass semantics right.

3. It'll run slowly because all the Python code is running through an interpreter, through a language that itself isn't blazingly fast.

I would've done this as an on-the-server compiler from Python to JS, using Python's built-in ast module to parse the source directly, translate to an intermediate representation, and output optimized Javascript. That seems to be the approach PyJS takes, which seems to be a much more mature and well-designed project.

What browsers need to do is to have a machine-level bytecode, so that they can download whatever interpreters are needed to run the scripting code the page uses. Then pages can be written in whatever language the developer feels is best.

This is the real potential of something like Native Client - although it doesn't look like that potential will be achieved any time soon.

It's pretty common now to call these "compilers".

https://github.com/clojure/clojurescript

http://www.haskell.org/haskellwiki/The_JavaScript_Problem

https://github.com/jashkenas/coffee-script/wiki/List-of-lang...