Zen of Python
The Zen of Python is a collection of 19 "guiding principles" for writing computer programs that influence the design of the Python programming language. Python code that aligns with these principles is often referred to as "Pythonic".
Software engineer Tim Peters wrote this set of principles and posted it on the Python mailing list in 1999. Peters' list left open a 20th principle "for Guido to fill in", referring to Guido van Rossum, the original author of the Python language. The vacancy for a 20th principle has not been filled.
Peters' Zen of Python was included as entry number 20 in the language's official Python Enhancement Proposals and was released into the public domain. It is also included as an Easter egg in the Python interpreter, where it can be displayed by entering import this.
In May 2020, Barry Warsaw (developer of GNU Mailman) used it as the lyrics to a song.
Principles
The principles are listed as follows:
Being Pythonic
One of the principles, "There should be one-- and preferably only one --obvious way to do it", can be referenced as the "Pythonic" way. The official definition of "Pythonic" is:
Code that is difficult to understand or reads like a rough transcription from another programming language is called unpythonic.
In practice
Since the release of the Zen of Python, there has been research done on its effectiveness and actual use among developers. Despite the difference in interpretation between beginners and experienced Python programmers, interviews among 13 Python programmers of varying skill show that the Zen of Python "positively influences the way developers write and talk about code". Researchers extended this case study to explore the use of Python idioms on GitHub repositories, and found that the usage of "Pythonic idioms" increased over time. Writing Python code that aligns with the Zen of Python may save memory and run time of Python programs. The desire to write in Pythonic code has led to refactoring tools to help programmers achieve this goal.