Polycompiler

See how it works on YouTube.

An experimental project to attempt to merge arbitrary Python and JS code into one source file.

For example, the following code prints Hello JS when run with Node, and Hello Python when run with Python 3.

1 // (lambda: exec("print('Hello Python')", globals()) or 1)()
lambda: eval("console.log('Hello JS')")

Installation & Use

Here's how you can get started with Polycompiler in a few simple steps.

Install polycompiler on NPM:

npm i polycompiler

Merge your files

Now, run the polycompiler command, providing the path to a JS file, a Python file, and an optional result file path.

• When the output is run with Node.js: It will run your JS file
• When the output is run with Python: It will run your Python file

polycompiler in.js in.py out.py.js

🚧 WIP: The current file convention for Polycompiler output file extension is .py.js. This is becuase Node refuses to parse files of other file extensions, so it has to end in js.

Test it out

First, running it in Node should execute your JS

node out.py.js

And, running it with python3 will execute the Python

python3 out.py.js

Why Polycompiler?

The best answer for this is honestly "for fun". However, it could also possibly be a possible solution for a single file that can be targeted to both Python and JS audiences (who may perhaps not have the other installed).

How does this work?

See my thought process in developing this on YouTube.

Let's work through this code to see how Polycompiler works:

1 // (lambda: exec("print('Hello Python')", globals()) or 1)()
lambda: eval("console.log('Hello JS')")

Running the Output in Python

First, let's consider what happens when we run this in Python:

• The first statement in of itself returns nothing, but the lambda function is executed, containing the eval with our target code
• The second statement is not run at all, since the lambda expression is not called. Thus, the "incorrect" JS code in the eval is never run

This effectively only runs the Python code.

Running the Output in JS

Now, let's consider what happens if you run the code in JS. It's shown in a JS syntax-highlighted codeblock for clarity.

1; // (lambda: exec("print('Hello Python')", globals()) or 1)()
lambda: eval("console.log('Hello JS')");

• The first statement, ignoring the JS comment, is simply an integer. It does nothing.
• The second statement utilizes a clever trick with JS Labeled Statements: The lambda: at the start is treated as a label and is ignored. The eval is executed like normal and delivers the execution of the JS code in a string.

This effectively only runs the JavaScript code.

Summary

And just like that, we've managed to ignore the JS portion in Python and the Python portion in JS. Pretty neat!

While it seems simple in hindsight, this solution took a long time to figure out (even though some aspects of it are hiding in plain sight), so I hope it's interesting!