brython

JavaScript that uses register based bytecode instead of stack based, supports optimizing the bytecode by inlining procedures and constant folding, and never allocates memory (all work is done in a single user provided preallocated buffer). This would require integrating multiple disparate coding concepts and not regurgitating prior art from the training data [1] https://github.com/skulpt/skulpt [2] https://github.com/brython-dev/brython [3] https://github.com/yzyzsun/PyJS

least some parts of it, and have time to spare, do take the time out to contribute to this project. It's pretty insane what they're building. You can join their Google Groups forum here: https://groups.google.com/forum/?fromgroups=#!forum/brython

ies. For Brython and Transcrypt, C parts of the standard lib have to be re-written in Python for compatibility. So when you're importing something from the itertools package, it's actually a custom implementation like this: https://github.com/brython-dev/brython/blob/master/www/src/L.... The custom code will not always be exactly compatible with the CPython implementation. * Incompleteness. Some std libs aren't implemented, or are only partially implemented. 3rd party libs that rely on these will not work. Popular 3rd party libs like sklearn which get their power by wrapping C/Fortran libraries need custom wrappers that don't exist (AFAIK) yet. * You still gotta JavaScript. Even in the best transpilation scenarios, things break and you have to figure out what the generated or interpreted code is doing. This is especially tough for Python in the browser tools, which aren't widely used, so have both undiscovered bugs and a lack of community support. In my experience, working in a transpiled codebase doesn't mean you have to learn one thing, but three: the source language, the target language, and the frankenstein monster of the logic/compromises bridging the two. * Tooling. The ecosystem hasn't reached a critical mass to support tooling. It's unclear if there's enough excitement in the Python community to get it there. With all that said, unless you're a true believer or just want to have a little fun (again, it is fun!), I wouldn't recommend this.

of the transpiler. It's pretty similar to Transcrypt except that it comes with a library which is a rewrite of GWT for Python. With that you end up writing web application in a similar way as you would do for desktop application. I've been using Pyjamas for years, it was working quite well (but you had to get used to some bugs/incompatibilities with Python, and I have not experienced that with Brython so far). About the library, while it seemed like a neat idea at the beginning, at the end it was an experience too distant from web developing, and meanwhile HTML and CSS improved a lot so it doesn't really makes sense anymore. So from my experience : - you want real Python 3 and being able to use it dynamically (in a live console for instance) ==> Brython - you want something as fast as javascript with clean syntax of Python ==> Transcrypt Both work well with JS libraries, Brython in addition re-implement most of Python standard API (but it's long to import, so it's often better to use JS libraries or native methods). In addition, and really subjectively, I find the Brython community really nice, the main developer is reactive and kind. Brython gives you real Python traceback, and you can even run pdb inside the browser (which will block your scripts) or an Inspector (a non blocking Python console) allowing to transfer objects between Python and Javascript for inspection in dev tools. edit: corrected the initial statement, Brython feels like an interpreter, but it's actually transpiling, so you don't have such a big performance impact. edit2: added that Brython can be compiled AOT from CLI too + precisions that I didn't compared with Transcrypt myself