I can't think of one canonical companion project for them, but early Lisp, COBOL, and FORTRAN were also pretty driven by external application concerns, in AI, business logic, and numerical simulation, respectively.
COBOL (and Ada) were standards-first languages. The industry-driven standards committees designed the languages first, and it was not until afterwards that there were working implementations, much less working programs. Industry experience guided them in later releases, but v1.0 (which Rust is still working towards) were even more ivory-tower than languages whose only program is their own compiler.
- Packaging: This is probably where I think Rails contributed most - both rubygems.org and Bundler were created to make it easier to manage the creation and use of lots of large numbers of dependencies, which Rails projects tend to have. Also rvm and its descendants were created to handle Rails app deployments, and are especially useful for situations where you're switching between lots of projects with different ruby version and library dependencies, which is typical in Rails client work.
- Standard library: The `Object#tap` method came from ActiveSupport. Also, ActiveSupport had an OrderedHash, and now all hashes are ordered. I think there are some other examples of that sort of thing.
- Performance: I really don't know what has driven performance improvements have been made, but it doesn't seem outlandish to think that backlash against poor CPU and (especially) memory usage characteristics of Rails applications was a contributor.
rubygems the tool existed before Rails, as did multiple gem hosting mirrors. I believe rubygems.org sprang up because rubyforge.org was falling out of favor. And Bundler is not part of Ruby.
It's possible Wayne Seguin created rvm due Rails but I never got that impression from his talks (but it's been some time).
Pretty sure MenTaLguY created "tap"; Rails had "returning" (though they are similar and perhaps the usage in Rails made it popular enough to warrant inclusion in core).
http://moonbase.rydia.net/mental/blog/programming/eavesdropp...
Certainly if any library gets a lot of use then that will influence aspects of the base language, but matz and ko1 seem pretty deliberate about what gets added.
You're probably right about `.tap`, and I can't think of any other standard library stuff, so my speculation there is seeming pretty weak.
I didn't suggest that Rails invented rubygems and gem hosts, I suggested that rubygems.org and bundler were major improvements to the ruby packaging ecosystem that were driven by Rails. I'm not sure you actually disagreed with that point...
Rubygems.org was not driven by Rails. It doesn't offer much beyond what rubyforge was doing. Less, actually. RF was for code hosting, docs, and gem serving. Once people started moving to github RF lost favor. When Github decided to stop serving gems rubygems.org came about to fill the gap. It lists and serves gesm; code and docs live elsewhere.
Bundler, sure, came form the Rails community to apparently solve a problem for that community. It's not for everyone, though.
I don't use it (doesn't make life any better for me), but then I don't use Rails either.
There's lots that goes in Ruby that has nothing to do with Rails and the conflation of Rails and Ruby is a detriment to different Ruby communities out there.
I think lots of people find Bundler to be an improvement over straight rubygems outside of Rails projects (even if you don't), which I think fits the criteria of "an improvement driven by Rails".
I think your last sentence is the real argument you're trying to make here, and I agree with it wholeheartedly - it's incredibly frustrating that so many people seem to think Ruby is only good or useful because of Rails. I'm not one of those people!
It's definitely an interesting aspect. For most languages, the only substantial project during their early life is their own compiler. There is an intriguing theory (posted on HN a few weeks back?) that this results in languages that are optimised for writing compilers, at the expense of writing other things.
Are there other examples of languages that had this kind of companion project in their early life? Did UNIX do this for C? To what extent did Rails do it for Ruby? Is there something inside JetBrains that does it for Kotlin, or inside JBoss that does it for Ceylon?