Rational Apex Ada is another dev platform that was way ahead of its time in early to late 90's. Multi-user hosted dev environment with incremental compilation and dependency tracking, syntax and semantic error highlighting, semantic search (i.e function signature) across whole repo, its own version control system with a git submodules style structure, automatic formatting as you write code. [Remote] Debugging and emulation features (stack trace, line of code, disassembly, etc), plus excellent VxWorks integration and tooling. Not to mention all the Ada language features which are still not available in modern languages.