Python is the fastest-growing programming language, and by 2019 will significantly outstrip other languages in terms of active developers.

That’s the prediction of programming Q&A hub Stack Overflow, based on the ballooning number of developers viewing questions about Python on its site. The extrapolation is based on a huge amount of data, Stack Overflow is the world’s largest online community site for developers, with more than 50 millions amateur and professional devs visiting the site every month.

“The term ‘fastest-growing’ can be hard to define precisely, but we make the case that Python has a solid claim to being the fastest-growing major programming language,” says Stack Overflow data scientist David Robinson in a blog post.

In the five years to June 2017, Python has gone from the least to the most popular of the top six programming languages, with a 2.5x increase in views of Python questions. Robinson says that these statistics relate to developers from “high-income” nations and are “generally representative of trends in the United States, United Kingdom, Germany, Canada, and other such countries”.

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The popularity of Python is, in part, due to its flexibility, with the language used regularly by web and desktop developers, sysadmin/devops, and more recently by data scientists and machine-learning engineers.

“It seems like Python is used in every domain — system operations, web development, deployment, scientific modeling, etc etc. There is no other language that is so versatile,” says Jacqueline Kazil, board director of the Python Software Foundation (PSF).

The rapid spread of Python also stems from its strong community, she says, as well as “the language itself, readability, conciseness, and the completeness of its standard library, which we call “batteries included”.

Python won’t just stay at the top, according to a predictive model put together by Stack Overflow’s Robinson, but will decisively consolidate its lead over other languages over the next two years.

While interest in Java and JavaScript is forecast to remain static, views of Python-related questions will continue to climb, and by 2019 will account for about 15 percent of all views on Stack Overflow, the model predicts.

“With a 27% year-over year-growth rate, Python stands alone as a tag that is both large and growing rapidly; the next-largest tag that shows similar growth is R,” says Robinson.

The data above also plots the decline of interest in once-popular languages, such as Ruby and Objective-C. The findings reinforce the notion that Ruby’s star is dwindling, with job postings and training courses falling and Stack Overflow figures showing a reduction in views on questions about Ruby since 2011. The shrinking interesting in Objective-C is attributed by Stack Overflow to it “being replaced by Swift as the language of choice for iOS development”.

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The varying fortunes of functional programming languages are also laid bare, with Scala pulling away at the front, F# and Clojure shrinking and Haskell holding fast in the middle.

One other outlier was TypeScript, whose growth in traffic was so impressive, 142% year-on-year, that Stack Overflow left it off to avoid “overwhelming” the scale.

The story in the rest of the world–in countries like India, Brazil, Russia and China–is slightly different, and is perhaps more reflective of recent developer surveys that put JavaScript/Java in pole position when it comes to in-demand languages.

However, even here Python is in the ascendant.

“Outside of high-income countries Python is still the fastest growing major programming language; it simply started at a lower level and the growth began two years later,” writes Robinson.

As with any language, Python has its limitations, for example, software written in Python is more computationally demanding and consequently runs more slowly than apps written in C++, due to Python not being compiled to machine code. The PSF’s Kazil says the language also needs to “expand its presence on mobile platforms”, something she says the Kivy software framework and BeeWare transpiler are helping address.

But Kazil doesn’t see uptake of Python slowing in the near future.

“Data science and scientific applications are an area of high growth. Python’s accessibility allows subject matter experts to focus on their relative subject matter areas in their research. This doesn’t seem like it will stop any time soon,” she says.

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