#typst.mbt

A port of the Typst typesetting engine to MoonBit. See PLAN.md for scope, architecture and status.

#Layout

Path	Contents
syntax/	Port of typst-syntax: lexer, parser, syntax nodes, spans, Lines, paths and file ids (path.rs), packages and manifests (package.rs)
syntax/ast/	Typed AST over the syntax tree (ast.rs)
unicode/	Unicode property tables generated from the Rust crates upstream uses
codecs/	Image codecs upstream gets from crates: PNG decode/encode (png, fdeflate), JPEG/GIF/WebP headers (zune-jpeg, gif, image-webp), EXIF (kamadak-exif), inflate
svg/	Port of typst-svg (so far: WebImage data URLs)
oracle/	Rust crate dumping upstream reference outputs (goldens)
tests/runner/	Differential runner comparing the port against the goldens
tests/packages/	Documents that use real packages of the Typst package registry (pinned in manifest.tsv), for the packages stage
kit/, kit/platform/	Port of typst-kit (files, packages, fonts, diagnostics) and OS access for native and wasm
cli/	Port of typst-cli: the typst command line
typst_assets/fonts/	The fonts embedded into the CLI (generated)
doc/fonts/	IBM Plex Sans, the sans-serif family of the EDSL's worlds (generated the same way; the CLI does not load it)
scripts/	upstream.sh (pinned checkout), goldens.sh (regenerate goldens)

#Command-line interface

cli/ is a port of typst-cli (on kit/, a port of typst-kit) that compiles documents from the file system. It builds for native, wasm-gc and wasm (the wasm builds run in moonrun):

moon run cli --target native --release -- compile input.typ output.pdf
moon run cli --target wasm-gc -- compile input.typ 'page-{p}.svg'
moon run cli --target native -- compile --format html --features html in.typ
moon run cli --target native -- eval 'query(heading).len()' --in input.typ
moon run cli --target native -- fonts --variants
moon run cli --target native --release -- watch input.typ output.pdf

Supported: compile/c (PDF, PNG, SVG, HTML, bundle; --root, --input, --font-path, --ignore-system-fonts, --ignore-embedded-fonts, --pages, --ppi, --pretty, --pdf-standard, --pdf-tagged, --creation-timestamp/SOURCE_DATE_EPOCH, --features, --deps, --diagnostic-format, - for stdin/stdout), watch/w (native and wasm; --no-fullscreen), eval, query, fonts, info, init (templates from local package directories) and the environment variables of upstream. Packages are served from the package data (@local, …) and cache directories; downloading packages from Typst Universe, update, completions, --open, --timings and the HTTP server of watch for HTML export (pass --no-serve) are not supported; --jobs is accepted for compatibility and has no effect (compilation is single-threaded). The embedded fonts are those of upstream (Libertinus Serif, New Computer Modern, DejaVu Sans Mono). On wasm, system font discovery reads every font file through moonrun's host API (slow; use --ignore-system-fonts), symlinks cannot be detected, the local time zone is UTC and only text can be written to stdout.

watch recompiles when a file that the last compilation read changes (sources, imported and included files, data files, images, package files), is replaced, removed or created, like upstream's, and prints the same status. Every recompilation starts from scratch (upstream reuses the results of the previous one). It watches files through moonbitlang/async, which only the CLI links: the wasm-gc build has no file system events and reports that watch is not supported. On macOS a watched file is an open file (kqueue): the native build raises its limit of open files to the hard limit, the wasm build runs with the limit of the shell (ulimit -n). On Linux every directory with watched files takes an inotify instance (fs.inotify.max_user_instances). The directory of a watched file must be readable. The wasm build cannot tell a symbolic link: it does not notice when the file that a link points to is replaced (written in place, it does).

#Documents as MoonBit code (experimental)

The doc package builds documents with typed MoonBit constructors and compiles them with the same engine, without Typst markup. The API is experimental and may change between releases; the design is in docs/edsl-design.md.

fn report() -> @doc.Document {
  @doc.Document([
    @doc.SetPage(paper="a5", margin=@doc.Sides(all=@doc.Cm(1.8))),
    @doc.SetHeading(numbering=@doc.Numbering("1.")),
    @doc.Heading("Build times"),
    (
      $|Running text is a multiline string; inline elements such as
      $|\{@doc.Emph("emphasis")} and \{@doc.Raw("code")} are interpolated.
    )
    |> @doc.Prose,
    @doc.Equation("sum_(k=1)^n k = (n(n+1))/2", block=true),
  ])
}

fn run() -> Unit raise {
  let world = @system.world(root=".", system_fonts=false, today=(2026, 10, 5))
  let compiled = report().compile_paged(world)
  @system.write("report.pdf", compiled.pdf().unwrap())
}

Import moonbitlang/typst/doc and moonbitlang/typst/doc/system (file and font access). Plain strings are literal text and are never parsed as markup; Markup(..) and Equation(..) are the explicit escape hatches. Besides Typst's embedded fonts the worlds of the EDSL have a sans-serif family, IBM Plex Sans (SetText(font=["IBM Plex Sans"])).

compiled.review_html() writes a self-contained preview page for reviewing a document: clicking or selecting rendered text shows the MoonBit call that produced it (file, line, and the source characters for string literals and Prose blocks), a comment can be attached, and the packaged feedback copied for the author. Keyed(key, ..) names the data row of loop-built content. See docs/edsl-review.md.

#Testing

scripts/upstream.sh            # checkout upstream at UPSTREAM_REV
scripts/goldens.sh             # needs Rust; or `scripts/goldens.sh syntax ast`
moon run tests/runner --target native -- syntax [filter] [-v]
moon run tests/runner --target native -- ast [filter] [-v]

The stages (scripts/ci/stages.tsv lists them with their case counts, and scripts/ci/stages.py runs them all): syntax, ast, reparse, eval, realize, html, bundle, paged (laid-out frames), svg, svg-replay, pdf-semantic, pdf-semantic-replay, pdftags, render, font, shape, shape-hb, break, usvg, usvg-images, resvg, wasm-validate, wasm-spec, edsl and packages. Most of them run on upstream's own test suite (some on the suites of the crates upstream uses). packages compiles documents that use real packages of the Typst package registry (touying, cetz, fletcher, codly, glossarium, mitex, cmarker, templates, ...; see tests/packages) and compares frames, SVG and diagnostics with upstream:

scripts/packages.sh            # fetch the pinned packages into .repos/typst-packages
scripts/goldens.sh packages    # needs Rust
moon run tests/runner --target native --release -- packages [filter] [-v]
scripts/packages_cli.py        # the same through the two CLIs: stderr, PNG pixels, times

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