There's such a strong connection between the idea of "programming language runtime" and "operating system" (resource management, I/O management, task scheduling

There's such a strong connection between the idea of "programming language runtime" and "operating system" (resource management, I/O management, task scheduling, package management, upgrade management, lifecycle management, version control, configuration management, user interface, etc.) that it makes sense both to - think of a PL as an OS (Smalltalk, Erlang, JVM) - think of an OS as a PL The latter leads to the idea that there might be a "main language" for an OS in the same way there's a "main language" for Smalltalk, Erlang, and JVM runtimes (Smalltalk, Erlang, and Java, respectively), and "auxiliary languages" that fit into the same runtimes (Java/Self/etc, Elixir/LFE/etc, and Scala/Clojure/Kotlin/etc, respectively).