The Format SDK is the high-level layer of datamark. It turns Markdown documents into typed objects — and back again — through reusable, self-testing format definitions.

A format is a typed contract: you define a schema, a parse function that walks the AST using the Parse SDK, and optionally a stringify function for round-trip serialization using builder primitives from datamark/stringify. Add inline examples and your format becomes self-documenting and self-testing.

datamark()

The format factory — typed config, parse, stringify, test, docs

Frontmatter

Reading, validating, and typing frontmatter with schemas

Parsing Patterns

Navigate the AST, extract data, map Markdown to objects

Stringify

Serialize back to Markdown with builder primitives from datamark/stringify

Testing

Inline examples, self-testing formats, and CI integration

What the Format SDK provides

Capability	Description
Typed frontmatter	`frontmatterSchema` validates and types `doc.frontmatter` before your `parse` function runs
Output validation	`schema` validates the return value of `parse()` automatically
Round-trip serialization	`stringify` turns typed data back into Markdown via `datamark/stringify`
Self-testing	`examples` are validated by `.test()` — add them once, test forever
Builder primitives	`heading()`, `list()`, `codeBlock()`, `frontmatter()` and more from `datamark/stringify`
Standard Schema support	Works with Zod, Valibot, ArkType, TypeBox, and any Standard Schema v1 validator

How the layers fit together

datamark/stringify  →  heading(), list(), codeBlock(), frontmatter() …
        ↑
   Format SDK      →  datamark({ schema, parse, stringify, examples })
        ↑
    Parse SDK      →  parse(), findAll(), textContent(), isCodeBlock() …
        ↑
    marked + yaml  →  Markdown lexer + YAML parser

The Format SDK is built on top of the Parse SDK. Every parse function receives a Document from the Parse SDK and uses its utilities (findAll, textContent, isCodeBlock, etc.) to extract data. Every stringify function uses datamark/stringify primitives to reconstruct Markdown cleanly.

For raw AST manipulation without schemas or serialization, use the Parse SDK directly.

Format SDK