For long term storage, the US Library of Congress recommends CSV, JSON, XML and... sqlite! https://www.sqlite.org/locrsf.html
I'm surprised since it's a more complex format tied to a single implementation. Extremely widespread though.
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Is there any relationship between language adoption and the size of its standard library?
These days it seems completely orthogonal, but early Java adopters spoke highly of the collections library compared with C++.
Maybe it's the widespread availability of package managers?
TIL Tcl has a notion of 'safe interpreters', a mode where you can run untrusted code in a sandbox: https://www.tcl.tk/man/tcl8.4/TclCmd/safe.htm
Not many programming languages have this, but it's way safer to include in the implementation than try to build as a userland library.
Bril is a cute intermediate language for teaching (think simplified LLVM IR): https://www.cs.cornell.edu/~asampson/blog/bril.html
The idea of providing a standard JSON format to help students write basic passes is really elegant.