Sather
Sather is an object-oriented programming language with a syntax similar to Eiffel. It is primarily used for high-performance computing and large-scale parallel and distributed systems.
Hello, world code example:
class GOODBYE_WORLD is
main is
#OUT+"Hello world!\n";
end;
end;
Popularity: Less than 1% of developers are using or have used this language.*
*According to StackOverflow's 2023 survey.