Python: Guido van Rossum's side-project language, built for readability, eats the world

In late 1989 Guido van Rossum, then in his thirties, was building the Amoeba distributed system at CWI, the Dutch national centre for mathematics and computer science. Every available tool frustrated him: C forced developers to manage memory by hand and re-invent basic libraries for each project, while the Unix shell ran too slowly for complex logic. Perl, the obvious high-level alternative, would not port to Amoeba — a gap van Rossum later called lucky for Python, because if Perl had ported, 'I would have never have thought of starting my own language.'

He had an unusual head start: three years on the CWI team that created ABC, an interpreted language, taught him how interpreters and syntax design work. So instead of waiting for better tools he decided to build his own — 'stealing my ideas from ABC but reducing the project size from something that took three years to complete to something I can do on my own, as a skunk works project in three months.' Python began in earnest in late 1989, named after Monty Python, coded in his spare time instead of watching television.

What he designed around was readability. Indentation groups code into blocks, enforcing clear formatting automatically; classes, exception handling, lambda/map/filter and a deep built-in library came from the start. Van Rossum has said programming languages are as much about communicating ideas between developers as about telling a computer what to do. He posted the language to the alt.sources newsgroup in 1991 under an open licence and built it up through regular releases and a fledgling mailing-list community that became the Python Software Foundation in 2001.

Python stayed the underdog through the 1990s — Perl first, Tcl second, Python a modest third — and won by staying maintainable as codebases grew: a 500-line project could stay readable in Python where Perl demanded enormous discipline. By 2019 it was the fastest-growing language by active developers in Stack Overflow's survey, used by Netflix, Instagram and NASA, and the tool that stitched together the first image of a black hole. Perl had shrunk to the point of vanishing from the same survey.