[musicale]

> no proprietary programming language has a large user base. The closest is probably Microsoft Excel, I'd guess.

MATLAB still has a large user base, although GNU Octave is basically an open source version.

The Wolfram (Mathematica) language also has a large user base. I am not aware of an open source implementation.

Swift is open source but developed by Apple and mainly used on their systems.

[namibj]

I did indeed forget MATLAB. Wolfram isn't that big, and if Swift should count, C# should too.