advanced pandoc2

meta.lua

-- read metadata file into string

local metafile = io.open('metadata.yaml', 'r')
local content = metafile:read("*a")
metafile:close()

-- new elements

local before = pandoc.RawInline('tex', '\\begin{otherlanguage}{english}')
local after = pandoc.RawInline('tex', '\\end{otherlanguage}')

-- get metadata

local default_meta = pandoc.read(content, 'markdown').meta

return {
  {
    Meta = function(meta)
      -- use default metadata field if it hasn't been defined yet.
      for k, v in pairs(default_meta) do
        if meta[k] == nil then
          meta[k] = v
        end
      end

      return meta
    end,

    Code = function(code)
        return {before, code, after}
    end,

    CodeBlock = function(code_block)
        return {pandoc.Para({before}), code_block, pandoc.Para({after})}
    end,

    RawBlock = function(raw_block)
        return {pandoc.Para({before}), raw_block, pandoc.Para({after})}
    end,
  }
}

metadata.yaml

---
date: "\\today"
lang: fr
babel-otherlangs: [en]
polyglossia-otherlangs:
- name: english
bibliography: src/bibliographie.yaml
csl: iso690-numeric-fr.csl

mainfont: Linux Biolinum O
sansfont: Linux Libertine O
monofont: Inconsolata
monofontoptions: Scale=0.9
---