For reasons I explained in last week’s notes, I cut another major release, 0.5.0, of Rheo this week. Probably most significant in this release is a change in how spines are specified in rheo.toml. A spine is the main conceptual extension that Rheo gives over Typst proper. It functions as a project management primitive, allowing you to split Typst across multiple files and then have the Rheo CLI automatically collect them together. If you’ve been following the latest features in Typst, you’ll know that this is fairly trivial to set up natively using a combination of the experimental bundle target and module system, which is more or less how Rheo compiles spines under the hood. Spines offer an abstract way to think about which files (‘vertebrae’) should be packaged into each format.
In 0.5.0, spines are inferred from the file system hierarchy of the content directory by default. I realized that this is usually what I want in my Rheo projects, and that this ‘spine inference’ gives Rheo more concrete utility over Typst; as maintaining spines explicitly translates the burden of tracking vertebrae into a different idiom (as was basically necessary in Rheo <0.5.0), rather than actually alleviating it. If you want to use the native Typst CLI to compile multiple Typst source files into a website with a corresponding number of pages, you need to set up a basic bundle/module template to import them appropriately. Using Rheo >=0.5.0, you can just run rheo watch . and get going.
I also added the rheo-context variable, which is the first step to comparably removing the need to explicitly set up a harness for tables of contents / sitemaps in sidebars and index pages. After a discussion with Will Crichton about this, I decided that I need to change the API in another breaking way this week, moving the data structure behind a rheo-context() function boundary. This is breaking for a variable that was only introduced in 0.5.0, though, and so I am considering subverting strict semver and batching the changes into an 0.5.1 release. Otherwise I might give the impression that a major version every week is Rheo’s standard development velocity, which is certainly not the case.