Write once, run anywhere has been a slogan for coming up on thirty years. Except all implementations of it have acceded to reality in one or more important aspe

Write once, run anywhere has been a slogan for coming up on thirty years. Except all implementations of it have acceded to reality in one or more important aspects, such as needing to install Java separately. And it's not just platform-specific compilation, it's everything that could support platform-specific compilation (if you've never tried to cross-compile from Linux to MSVC, you should), and also all sorts of platform-specific code (like console functions vs terminal sequences, or even stuff as banal as $HOME vs $USERPROFILE). Cosmopolitan still isn't perfect, because it doesn't emulate all of Linux, so you still need kernel32.dll here and there. But it is still the best of any attempts.