The summit

You have installed a compiler, written a script, used a prompt, learned the values and the control flow, the errors and the optionals, the structs, enums and traits, the ownership rules, the collections, built a calculator and a to-do list, parsed binary data, computed at compile time, written tests, read effects, run threads, served HTTP, drawn a window, made a package, shipped a library to three other languages, and trained a neural network. That is the language. There is no chapter on advanced features that the rest of us were keeping from you.

What to read now#

• The language reference: every construct, one paragraph each. It is the page to keep open while writing.
• The standard library: every module and function, from the doc comments in std/.
• The specification: what the language promises, in the words the test suite is written against. Section 5 (ownership), 8 (effects) and 12 (what undefined behaviour is and is not) are the ones that repay a careful read.
• How Nexium works: the compiler stage by stage, for when you want to change it.
• Stability and platforms: what a version number means, which targets are tested.

What is coming#

The roadmap is public and specific. The next few themes:

• 1.1, the ergonomics the compiler wanted while it was being written in itself: a?.b, tuple destructuring, derive(Clone), iterators, slice patterns, more proofs so fewer functions carry panics.
• 1.2, memory safety without a garbage collector: the view rules, so that a slice or pointer cannot outlive its storage and unsafe marks everything the compiler cannot prove, without a borrow checker's annotations. Chapter 8 said where the 1.0 compiler stops; 1.2 is where it stops stopping.
• 1.3, the toolchain grown up: incremental builds, a semantic language server, nx bench, sanitizers.
• 1.4, the standard library people stop supplementing; 1.5, platforms (WebAssembly, more GUI backends); 1.6, the runtime that release builds deserve; 1.7, the seam both ways: what chapter 20 shipped to Python and Rust grows to NumPy, exceptions and handles, error enums and no_std, more languages out, and Python and Rust called from Nexium.

Each release has a name from the mountain the project has been climbing, and the names document explains the scheme; this book is a topo because the releases are a route.

Joining in#

The repository is github.com/Londopy/nexium. Contributing says how a change gets in: an example with recorded output or a compile-fail case, a changelog line, a language change needs the constraint it serves, and the contributor license agreement signed by a comment on the pull request. Bugs go in the tracker; open ones the maintainers know about are listed in known issues, and security reports have their own path.

The compiler is written in the language this book teaches, and its test harness and fuzzer are too. If you want to know how a feature really works, self/check.nx has the answer, and after these chapters you can read it.

Thanks for climbing.