I was a fan of Seven Languages in Seven Weeks [1] because it exposed you to different paradigms which you could then try to apply where they made sense on whatever tools you were using or building: prototype based, fault tolerante, funcional, logical. Very fun book when used right.

The point being that sometimes the tools themselves don't need to survive because you take the lessons from one thing to another (e.g. move semantics and rust/modern c++)

[1] - https://pragprog.com/titles/btlang/seven-languages-in-seven-...

Well, IPv4 is obsolete.