I would like to join in support of this post. I am eager to learn about Swift and it’s inner workings to be able to develop stable library wrappers. Wide number such wrappers is, in my opinion, essential for usability of Swift on non-mac platforms. Such task however requires in depth knowledege of Swift. I have posted about this in the past, for example: Swift ABI documentation .
Materials about Swift’s inner workings are scattered, old and outdated, in “TODO” state for years or in a form of hypertext link to the compiler’s source code Swift.org - Swift Compiler.
Lack of knowledge of C++ and LLVM is a me problem, however, complete and updated documentation of things such as memory layout, type metadata, the Swift Runtime and SIL passes and optimizations would help me a lot.