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engine

The pure-Go (CGO_ENABLED=0) TeX engine. A faithful re-implementation of TeX that loads and runs the genuine LaTeX classes — \documentclass{article}, {report} and {book} execute the real, embedded .cls files (LPPL, verbatim) — not an emulation — in native builds and in the browser via js/wasm, with no TeXLive and no server.

What it does

  • Runs the standard base classes for real. article, report and book load and execute the genuine embedded LaTeX .cls files, typesetting a numbered title, a dotted \tableofcontents, numbered sections/subsections, \chapter (report/book), numbered figure/table captions, itemize/enumerate, and math.
  • A full pipeline. A category-code mouth and gullet, a scaled-point stomach with Knuth–Plass line breaking and a cost-based page builder, \halign tables, math via math (vector output), OpenType fonts (a built-in default font, kerning, ligatures), and PDF + SVG output — the SVG carries a source map for click-to-line.
  • In the browser. A self-contained js/wasm build renders real LaTeX classes client-side — no TeXLive, no server.

Pipeline stages

Each stage is gated by an objective oracle.

Stage Status What it covers
Mouth + gullet ✅ done Category-code tokenizer, eqtb, macros (delimited parameters, full expansion), conditionals, registers, grouping.
Stomach ✅ done Box/glue/penalty model in scaled points, Knuth–Plass line breaking, a cost-based page builder, \halign tables.
Math ✅ done $…$ and display environments delegated to math (vector output).
Fonts ✅ done OpenType via go-opentype; a built-in default font, kerning and ligatures — runs with no assets.
Output ✅ done PDF (embedded subset fonts, selectable text) and self-contained SVG pages with a click-to-line source map.
Real classes ✅ done \documentclass{article\|report\|book} loads and runs the genuine embedded LaTeX class, native and js/wasm.

Fidelity gates

  • a byte-exact conformance ratchet (TestConformance), TeX snippets checked byte-for-byte against real-TeX output; and
  • a whole-document prose fidelity check against a real LaTeX engine (tectonic). On a sample of real arXiv article papers, the real class reproduces about 90% (median) of the reference engine's prose words.

Roadmap

The engine loads and runs the standard base classes; it is functional-parity-oriented and held to real-LaTeX fidelity, not a claim of full TeXLive parity.

  • amsart run as a real class (it additionally needs amsmath).
  • Heavy packages (tikz, hyperref, …) run as real files rather than native stubs.
  • A broader real-document conformance corpus (PDF-diff against pdftex/xetex) and the TRIP test.

Install

go get github.com/go-tex/engine

Requires Go 1.26.4 or newer. CGO_ENABLED=0, go vet clean, CI green across three 64-bit arches under QEMU (riscv64/ppc64le/s390x) plus macOS, Linux and Windows, and both js/wasm and wasip1/wasm.

Note

See the module's README for full, up-to-date details.