__
/\ \__
\ \ ,_\    __     _ __   ____     __    ___
 \ \ \/  /'__`\  /\`'__\/',__\  /'__`\ /'___\
  \ \ \_/\ \L\.\_\ \ \//\__, `\/\  __//\ \__/
   \ \__\ \__/.\_\\ \_\\/\____/\ \____\ \____\
    \/__/\/__/\/_/ \/_/ \/___/  \/____/\/____/

A parser combinator library for TypeScript, inspired by Parsec.

Install

npm install tarsec

Hello world

import { str, seqR, space } from "tarsec";

// define a parser
const parser = seqR(
    str("hello"),
    space,
    str("world")
);

// then use it
parser("hello world"); // success
parser("hello there"); // failure

Learning tarsec

• A five minute introduction
• The three building blocks in tarsec
• API reference

Features

• tarsec is entirely TypeScript. There's nothing to compile.
• Derived types: tarsec will generate TypeScript types for your parser
• Debug mode that prints what's happening step-by-step
• Tools to debug your parser's performance
• peek / not lookahead for disambiguating grammars without backtracking
• A way to make your parser more secure.
• Pretty error messages

Examples

• A CommonMark-ish markdown parser — importable as tarsec/parsers/markdown. Supports headings (ATX 1–6 with optional trailing # stripping, plus setext), fenced and indented code blocks, multi-backtick inline code spans, multi-line / nested block quotes, ordered / unordered / nested lists, pipe tables with alignment, horizontal rules, HTML passthrough, VitePress-style YAML frontmatter, plus inline bold/italic (* and _), combined ***bold-italic***, strikethrough, escapes, autolinks, hard and soft line breaks, images and links with optional "title", and reference-style links / footnotes resolved in a post-parse pass. Paragraphs round-trip soft-wrapped lines through an inline-soft-break node. Inline emphasis, strike, and link content all nest, so **[link](u)** and *a `code` b* round-trip into the AST.

Read more about use cases for tarsec.

Contributing

PRs for documentation, tests, and bug fixes are welcome.