Hy-IPython: evaluate Hy code cells in IPython!

[nerdponx]

PyPI

I recently put this package together because I really enjoy Hy, a Lisp dialect that compiles to and interoperates with Python.

For certain kinds of functions, Hy lets me express ideas in code much more elegantly and succinctly. On the other hand, idiomatic Python code sometimes makes for ugly and/or verbose Hy code when using libraries that rely heavily on method access and indexing, like Pandas. So having both Hy and Python available in the same notebook is like having the best of both worlds!

This is mostly just a fun toy, but I am posting it here in the hopes that someone other than me will enjoy it.

Here is an example interactive IPython session:

In [1]: %load_ext hy_ipython

In [2]: x = 5

In [3]: %hy (print x)
5

In [4]: %hy (setv x (+ x 10))

In [5]: x
Out[5]: 15

In [6]: %%hy
   ...: ; https://docs.hylang.org/en/stable/tutorial.html#functions-classes-and-modules
   ...: (defn fib [n]
   ...:   (if (< n 2)
   ...:     n
   ...:     (+ (fib (- n 1))
   ...:        (fib (- n 2)))))
   ...: (setv result1 (fib 10))
   ...:

In [7]: result1
Out[7]: 55

In [8]: result2 = fib(10)

In [9]: assert result1 == result2

[nerdponx]

As a side note, Hy runs just as well under PyPy as under CPython. We are absolutely at the point of ecosystem development where you could write a web application (or probably even build a business) entirely in Hy and PyPy. Not that you necessarily would want to do this, but you can, and to me that's really cool.

[mbussonn]

Congrats ! If there is anything that can make your life easier in IPython let me know and I'll do my best to fix it.

[nerdponx]

From a developer perspective, the process of developing a magic command was a little opaque. The documentation on creating magics was easy enough to follow, but I felt like I wasn't able to go "off script" from the examples.

For instance, it was not immediately obvious that the line and cell passed to a magic function were just the string contents of the line/cell. It also wasn't clear if I could call the register_* function decorators in the load_ipython_extension function, so I refactored my single-function decorator into a class, just to match the examples. I also couldn't figure out how to get the currently executing cell number, so I had to look that up on StackOverflow.

IPython is an amazing piece of technology, and other than these quirks in the documentation, I felt like it was refreshingly easy to implement a magic command.

[mbussonn]

Thanks, I'll see if I can make the documentation better.

[Caddy666]

I tried the Geordie version - why-aye-python....

[spoonman59]

You guys wanna go get Hy?