But one of the core constructs of a language is "how libraries work". In practice Arc could have plenty of libraries if Arc had a process for accepting contrib

But one of the core constructs of a language is "how libraries work". In practice Arc could have plenty of libraries if Arc had a process for accepting contributions from the community. Right now Arc is technically open source, but it does not work like most open source projects in the sense that there is no way to contribute yourself. Which is okay, but encouraging a community of programmers to use it and then not letting the excited ones help in any way is kind of a tease.