Colophon

This printing is true for one toolchain, and these lines are it — each implementation also naming the revision of the other it was tested against:

$ wolf --version
wolf 0.1.0 (wolfgang)
paired with lupin 0.1.8 (reference interpreter), pin 7886559
$ lupin --version
lupin 0.1.10 (wolf-interp, reference interpreter at pin 613c3dc)

The two lines name different interpreter releases on purpose. Each tool reports the revision of the other that it was differentially tested against, and those tests happen one release apart: the interpreter here is 0.1.9, and the compiler’s last differential run was against 0.1.8. §1.2 teaches the reader to read the pair that way. This page prints them as they are.

The exact revisions — the compiler, the interpreter, and the wolf grammar vendored from wolf-lsp — are recorded in wolf-toolchain.toml at the repository root. Every code sample, every console run, and every diagnostic on these pages was executed against them by CI; the samples runner’s report is the guarantee, not this sentence. The surface grammar in Appendix A is copied from the specification at the same revision, and the diagnostic codes in Appendix C are checked against the compiler’s own catalog in the same run.

Five chapters and three sections in this edition are reserved rather than written, each one saying on its own page what it covers and why it is not here. Their section numbers are anchors and will not move when the pages arrive.

Setting

The text is Charter; code is Source Code Pro, self-hosted so the web edition and the PDF set code identically. The web edition is canonical and is built with mdBook, with syntax highlighting done at build time from the same grammar the editor tooling uses — no highlighter runs in the reader’s browser. The PDF is set with typst from the same markdown. All three artifacts build on every commit, and the PDF’s absence fails the build.

License

Code samples are GPL-3.0-or-later with the wolf Runtime Library Exception, matching the runtime, so code you take from this book into your own programs is yours. The license for the prose is recorded in the repository, and the repository is the authority for both.

Errata

Corrections and reports: https://github.com/wolffe-lang/wolf-book/issues. The errata page states which kinds of report the book acts on and what a printed copy promises between reprints.