cmark-gfm-hs

============

This package provides Haskell bindings for [libcmark-gfm], the reference

parser for [GitHub Flavored Markdown], a fully specified variant of Markdown.

It includes sources for [libcmark-gfm] and does not require prior

installation of the C library.

cmark provides the following advantages over existing Markdown

libraries for Haskell:

  - **Speed:** cmark can render a Markdown version of *War and Peace* in

    the blink of an eye.  Conversion speed is on par with the

    [sundown] library, though we were unable to benchmark precisely,

    because [sundown] raised a malloc error when compiled into our

    benchmark suite. Relative to other Haskell Markdown libraries:

    cmark was 82 times faster than [cheapskate], 59 times faster than

    [markdown], 105 times faster than [pandoc], and 3 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.)  [libcmark-gfm] has been extensively fuzz-tested.

  - **Accuracy:**  cmark passes the CommonMark spec's suite of over

    600 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.

  - **Multiple renderers.**  Output in HTML, groff man, LaTeX, CommonMark,

    and a custom XML format is supported. And it is easy to write new

    renderers to support other formats.

  - **Ease of installation:** cmark is portable and has minimal

    dependencies.

cmark does not provide Haskell versions of the whole [libcmark-gfm]

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,

or enabling `optSafe` to filter out all raw HTML and potentially

dangerous URLs.

**A note on stability:**  There is a good chance the API will change

significantly after this early release.

[GitHub Flavored Markdown]: https://github.github.com/gfm/

[libcmark-gfm]: http://github.com/github/cmark

[benchmarks]: https://github.com/jgm/cmark/blob/master/benchmarks.md

[cheapskate]: https://hackage.haskell.org/package/cheapskate

[pandoc]: https://hackage.haskell.org/package/pandoc

[sundown]: https://hackage.haskell.org/package/sundown

[markdown]: https://hackage.haskell.org/package/markdown

[commonmark.js]: http://github.com/jgm/commonmark.js

[xss-sanitize]: https://hackage.haskell.org/package/xss-sanitize

[discount]: https://hackage.haskell.org/package/discount