Typst, the programming language and compilation toolchain that underwrites Rheo, natively and fully supports PDF. By default, Rheo generates one PDF per Typst source file in your project – much like running the Typst compiler directly.
What Rheo adds
Where Rheo goes beyond the standard Typst CLI is in its ability to merge multiple source files into a single PDF. This is useful when you want to separate sections of your book into individual files – for example, so that each section can also appear as its own web page in the HTML output – while still producing a unified document for print.
By default, Rheo does not use a spine for PDF – each source file is compiled independently. You can specify a spine in order to reticulate multiple source documents into a single output PDF by indicating the vertebrae and setting merge to true:
[pdf.spine]
title = "My book"
vertebrae = ["intro.typ", "chapters/*.typ"]
merge = trueWhen files are merged in this way, relative links between source files are automatically resolved to internal document links that point to the relevant section in the output PDF.
Rheo also copies any assets matched by your copy patterns into the PDF build directory.