You could have a multi-paradigm programming language and use FP techniques in the code. And at least in my university there was an introduction to FP and i assume that is true for most CS degree programs.
Anyway no offence but i wonder how many of the people who upvoted you actually programmed in a purely functional programming language . i read and did the exercises for real world haskell and i don’t think purely functional programming language can create the clearest code. i can see the advantages but a language with a strong support for FP and OOP would be better IMO (Ruby?). I also can’t think of a popular FOSS project that uses a purely functional language (pandoc is an exception, but that seems like a sweet spot for FP).
But it is a cool project and i like the endeavor.
Probably because the website site is listed as one of the repositories.