cmark-hs

This package provides Haskell bindings for libcmark, the reference parser for CommonMark, a fully specified variant of Markdown. It includes sources for libcmark (version 0.18.1) and does not require prior installation of the C library.

cmark provides the following advantages over existing Markdown libraries for Haskell:

• Speed: Conversion speed is on par with the sundown library. We were unable to measure precisely against sundown, which raised a malloc error when compiled into our benchmark suite. Relative to other implementations: cmark was 82 times faster than cheapskate, 59 times faster than markdown, 105 times faster than pandoc, and 2.8 times faster than discount.

• Memory footprint: Memory footprint is on par with sundown. On one sample, the library uses a fourth the memory that markdown uses, and less than a tenth the memory that pandoc uses.

• Robustness: cmark can handle whatever is thrown at it, without the exponential blowups in parsing time that sometimes afflict other libraries. (The input bench/full-sample.md, for example, causes both pandoc and markdown to grind to a halt.)

• Accuracy: cmark passes the CommonMark spec's suite of over 500 conformance tests.

• Standardization: Since there is a spec and a comprehensive suite of tests, we can have a high degree of confidence that any two CommonMark implementations will behave the same. Thus, for example, one could use this library for server-side rendering and commonmark.js for client-side previewing.

• Ease of installation: cmark is portable and has minimal dependencies.

cmark does not provide Haskell versions of the whole libcmark API, which is built around mutable cmark_node objects. Instead, it provides functions for converting CommonMark to HTML (and other formats), and a function for converting CommonMark to a Node tree that can be processed further using Haskell.

A note on security: This library does not attempt to sanitize HTML output. We recommend using xss-sanitize to filter the output.

A note on stability: There is a good chance the API will change significantly after this early release.