Guy Steele's talk "Growing A Language" gets into this. It's definitely worth looking up if you haven't seen it. I think we've seen two ways languages have succ

Guy Steele's talk "Growing A Language" gets into this. It's definitely worth looking up if you haven't seen it. I think we've seen two ways languages have successfully been open to evolution: Java was specifically designed to allow it to build on the standard library over time in fully backwards-compatible ways. It has required the central governance committee to adopt proposals, because reflection is slow and poorly-optimized, but it is a far more fully-featured language today than it was an inception without ever needing a reset. By keeping the surface area small & the strong "Everything Is An Object" paradigm in place, it has had remarkable longevity and has avoided the Python versioning pain. The second are the "sharp knives" languages: Javascript, Ruby and to a lesser extent C++ (only because DLL hell is very real). All three of these can be used to write software in any paradigm (including Aspects, if one is a masochist), and so let engineers invest in their own productivity. Languages where the standard libraries are indistinguishable from custom libraries require more skill and collective team alignment to use productively and safely, but also allow for solutions highly-opinionated languages can't support.