lex

lex is a plain text document format for structured documents. It combines the immediacy of plain text with the rigor of hierarchical, machine-readable markup so you can stay in the flow from first note to published artifact.

lex documents rely on indentation and a small set of markers to reveal structure. The syntax stays invisible so authors focus on ideas, not delimiters.

Hierarchical sections with numbered titles.

Term:
The definition follows immediately after the colon, indented one level.

- Unordered item
- Another item

1. Ordered item
2. Another ordered item
a. Nested alphabetical
b. Another nested

Example Code:
function hello() {
return "world";
}
:: javascript

The reference implementation lives in Rust crates under the lex-fmt organization. Each crate focuses on a specific role in the toolchain:

Definition

lex-core

Parser with a five-phase pipeline.

Definition

lex-babel

Format conversion for Markdown, HTML, PDF, and more.

Definition

lex-analysis

Document analysis powering editor features.

Definition

lex-lsp

Language Server Protocol implementation.

Definition

lex-cli

Command-line interface.

Definition

lex-config

Configuration loader shared by the CLI and tools.

All crates are published to https://crates.io/search?q=lex-.

• - Invisible syntax: Structure emerges from indentation and textual conventions.
• - Graceful degradation: Unmatched constructs become paragraphs instead of errors.
• - Complete lifecycle: Scales from quick notes to finished documents.
• - Tool-friendly: Deterministic grammar for reliable parsing.
• - Future-proof: Plain Unicode text, no proprietary containers.

lex is open source. See each repository for license details.