I think there are plenty of programming languages (maybe even most of them?) which take backward compatibility as a very serious goal. Obviously there's a balan

I think there are plenty of programming languages (maybe even most of them?) which take backward compatibility as a very serious goal. Obviously there's a balance between "don't break user space!" and fixing major problems (e.g., C's gets()), and most of the major ones seem to lean toward the former. At the company I work at, we've got a large amount of Fortran code from the '70s that works fine with the latest and greatest Fortran compilers (barring deprecation warnings which help guide refactoring efforts). Same with C/C++ from the '80s.