Pandoc filter to insert toc openxml in the beginning of document

docx-toc.hs

import Text.Pandoc.JSON

tocXml :: String 
tocXml = "<w:sdt><w:sdtPr><w:docPartObj>"++
	"<w:docPartGallery w:val=\"Table of Contents\" /><w:docPartUnique />"++
	"</w:docPartObj></w:sdtPr><w:sdtContent><w:p><w:pPr>"++
	"<w:pStyle w:val=\"TOCHeading\" /></w:pPr><w:r>"++
	"<w:t>Table of Contents</w:t></w:r></w:p><w:p><w:r>"++
	"<w:fldChar w:fldCharType=\"begin\" w:dirty=\"true\" />"++
	"<w:instrText xml:space=\"preserve\"> TOC \\o \"1-3\" \\h \\z \\u "++
	"</w:instrText><w:fldChar w:fldCharType=\"separate\" />"++
	"<w:fldChar w:fldCharType=\"end\" /></w:r></w:p></w:sdtContent></w:sdt>" 

tocBlock :: Block 
tocBlock = RawBlock (Format "openxml") tocXml

go :: Pandoc -> Pandoc
go (Pandoc meta blk) =Pandoc meta (tocBlock:blk)
-- One could also replace header with text "toc"
-- go :: Block -> Block
-- go (Header 1 _ [Str "toc"]) = tocBlock

main :: IO ()
main = toJSONFilter go