Pyrlang - Erlang node in Python

This is a drop-in Erlang node implementation in Python 3.5, designed to allow interoperation between existing Python projects and BEAM languages: Erlang, Elixir, Alpaca, Luaerl, LFE, Clojerl and such.

With just a few lines of startup code your Python program becomes an Erlang network node, participating in the Erlang cluster.

Documentation

http://pyrlang.readthedocs.io/en/latest/

Features

• Based on gevent which supports Python 2 and 3; Although used type specs in Python code raise required Python version to 3.5
• Erlang distribution protocol for R19 and R20+
• Registry of Python 'processes', which are gevent Greenlets and have a pid and an optional registered name
• Can inherit from Pyrlang.Process to create simple process-like Python objects
• Send and receive messages locally and remotely by pid or name;
• Supports net_adm pings
• Supports RPC calls. An RPC call can propagate an exception from Python to Erlang;
• Pyrlang.gen module has a helper to process gen_server-style calls

Erlang	Python	Notes
Atom	Pyrlang.Atom	Can use str() or access text_ field directly. Can decode UTF-8 atoms too
Float	Python float
Integer (small, big)	Python integer	Python is capable if big integers too
List (well formed)	Python list	Use helper functions in Pyrlang.Term.list module to convert to string
List (improper)	tuple (list, Pyrlang.AnyTerm)	A tuple with list and the tail element of the improper list
		Sending an improper list to Erlang requires use of Pyrlang.ImproperList helper
String	Python list	Use helper functions in Pyrlang.Term.list module to convert to string
Tuple	Python tuple
Map	Python dict
Binary	Python bytes
Bitstring	tuple (bytes, int)	A tuple of bytes and last_byte_bits:int defining incomplete last byte
		Sending a bitstring to Erlang requires use of Pyrlang.BitString helper
Pid	Pyrlang.Pid	Always long external Pids with a node name in them
Reference	Pyrlang.Reference	Always long external Refs with a node name in them
Lambda (fun)	Pyrlang.Fun	A class which holds parsed fun fields, not usable or useful in Python
	Any other object	Any unknown Python object will be encoded as {'Classname', #{field1 => value1...}}

Building

Install requirements via: pip3 install -r requirements.txt, this will also pull requirements for Sphinx documentation generator (not needed if you only use the library).

To operate Pyrlang only requires gevent and greenlet (dependency of gevent). NOTE: type specs in Pyrlang code require Python 3.5 so it will not really work on Python 2.

Source for the documentation is in the docs/ directory. It uses sphinx documentation generator. In docs/ run make html or just make.

Examples

Running make example1 will run a simple test which starts a node at py@127.0.0.1. See top comment in examples/01_simple_node.py.

Running make example2 will create a MyProcess Python class inherited from Process, register self under a name and await for message from a connected Erlang node (see top comment in examples/02_registered_process.py)