Lua filter to clean-up the Lua manual markup

lua-manual-cleanup.lua

-- There is no glyph for pi in the default font, but there is one in the
-- math font.
function Emph (e)
  local s = e.content[1]
  if #e.content == 1 and s.tag == 'Str' and s.text == 'π' then
    return pandoc.RawInline('tex', '$\\pi$')
  end
end

-- No glyph available for `≤` in the monospaced font.
function Code (c)
  c.text = c.text:gsub('≤', '<=')
  return c
end

function Header (h)
  -- The header is wrapped in a span containing the id. Use that id
  -- instead of the one automatically assigned by pandoc. Some headers
  -- start with the section number and an em-dash, so the span is the
  -- fifth element (Lua multipass).
  local span
  if h.content[1].tag == 'Str' and h.content[1].text:match '[%d%.]+' then
    span = h.content[5]
  else
    span = h.content[1]
    h.classes:insert('unnumbered')
  end

  h.identifier = span.identifier
  h.content = span.content

  return h
end

-- Remove menubar
function Div (d)
  if d.classes:includes 'menubar' then
    return {}
  end
end

-- Cleanup metadata
function Pandoc (doc)
  -- comma separated authors
  local authors = doc.blocks[2]
  authors.content:remove(1)  -- remove 'by'
  doc.meta.author = pandoc.List()
  for author in pandoc.utils.stringify(authors):gmatch '[^,]+' do
    doc.meta.author:insert(author)
  end

  -- remove title, authors
  doc.blocks:remove(2)
  doc.blocks:remove(1)

  -- add subtitle image
  doc.meta.subtitle = pandoc.MetaInlines{
    pandoc.RawInline('tex', '\\vspace{1em}'),
    pandoc.Image("Lua logo", "https://www.lua.org/images/lua-logo.gif")
  }
  return doc
end

run-pandoc.sh

docker run --rm --volume "$PWD":/data -u $(id -u):$(id -g) pandoc/latex \
    --toc \
    --toc-depth=2 \
    --metadata=documentclass=report \
    --pdf-engine=xelatex \
    --lua-filter=lua-manual-cleanup.lua \
    --number-sections \
    --top-level-division=chapter \
    --output=lua-5.4-manual.pdf \
    "https://lua.org/manual/5.4/manual.html"