Design overview

diagrams.mbt gives MoonBit a library for diagrams. It supports formats such as Mermaid, PlantUML, Draw.io and Graphviz DOT. This page describes the proposed design.

One diagram, start to finish

A program reads diagram text in one format, works on a typed diagram model, and writes the model in the same format or in another one.

// Read Mermaid text, then write it as Graphviz DOT.
fn convert(source : String) -> String raise {
  let diagram = @diagrams.read(Mermaid, source)
  @diagrams.write(Dot, diagram)
}

The library does these steps in this order:

Step	What happens
Read	Parse the source text of one format. Keep the source for reproduction.
Model	Build an immutable value with nodes, edges and labels.
Check	Report structured findings, such as an edge to a missing node.
Write	Write deterministic text for the target format.

Design principles

Domain logic is pure over explicit inputs and immutable public values.
Library code builds and tests on the wasm, wasm-gc, js and native targets.
Process and filesystem access stay in host adapters.
The published library has no user interface.