[jez]

The goals of library authors are frequently different from those of application developers. Library authors usually have to consider how to make their code work on more environments, on older language versions, more configurable, handling more edge cases.

I think there’s definitely value to reading a language’s standard library, and I’ve also gotten lots of value from even reading the language’s implementation! But I hope people take this advice to start with reading the standard library with a grain of salt: it can be one extra resource for you, and likely to show you new things that weren’t written in docs somewhere, but if it doesn’t click or is proving difficult to understand, that’s fine!

In particular, for the “reading code to learn” bit, consider reading an application written in that language (command line tool, web application, etc.) and it might serve as a more reduced intro to the language.