YAML front matter

[gregwebs]

This adds a yaml dependency. Should it be a separate package then? What should it be called?

Or would it be better for markdown to roll its own frontmatter parser that assumes a simpler YAML

renderMarkdownFile ∷ FilePath
                   → IO ((M.HashMap Text Text), Html) -- HashMap is YAML frontmatter
renderMarkdownFile filename = do
    contents ← shelly (readfile filename)
    let (frontMatter, rest) = case LT.stripPrefix "---" contents of  
            Nothing → (mempty, contents)
            Just firstMarkerStripped →
                LT.breakOn "---\n" (LT.stripStart firstMarkerStripped)
    let mResult = decode $ encodeUtf8 $ LT.toStrict $ frontMatter
    return (maybe M.empty id mResult, markdown def { msXssProtect = False } rest)

[snoyberg]

I'm on the fence about this one... but I think for now it makes more sense as a separate package.

[gregwebs]

what about adding a simple frontmatter parser to the existing package? I have only seen frontmatter used for key: string where string does not have to be quoted when it has spaces, so the common case seems to be both simple and not actually YAML.

[snoyberg]

I have no objection to that.

[gregwebs]

The code above works ok for me now. This issue can serve to document a workaround and a feature request.

[snoyberg]

I've moved the content to the Wiki: https://github.com/snoyberg/markdown/wiki/YAML-front-matter