remove haskell filter

output.html

@@ -6,28 +6,19 @@ ullamcorper felis, ac ultrices turpis congue vel. Nulla id tempus orci.
 Curabitur ac vulputate tellus. Integer fermentum tempor facilisis. Duis
 egestas luctus tristique. Maecenas vitae arcu sit amet justo feugiat
 imperdiet. Nunc luctus erat sed ligula convallis hendrerit.</p>
-<div data-include="filter.hs , filter.lua , ,">
-#!/usr/bin/env runhaskell
--- filter.hs
-import Text.Pandoc.JSON
-import qualified Data.Text.IO as TIO
-import qualified Data.Text as T
+<div data-include="README.md , filter.lua , ,">
+# Piecewise Readable Filter
 
-file2Block :: FilePath -&gt; IO [Block]
-file2Block f = do
-    contents &lt;- TIO.readFile f
-    return [Plain [Str contents]]
+This is a pandoc filter manipulating
+[fenced_divs](https://pandoc.org/MANUAL.html#extension-fenced_divs) in
+pandoc markdown.
 
-doInclude :: Block -&gt; IO Block
-doInclude cb@(Div (id, classes, namevals) contents) =
-    case lookup (T.pack "include") namevals of
-    Just f  -&gt; Div (id, classes, namevals) &lt;$&gt; file2Block
-(T.unpack f)
-    Nothing -&gt; return cb
-doInclude x = return x
+Inspired by [this
+joke](https://www.zhihu.com/question/586807834/answer/2973535981).
+
+useful refs:
+- https://pandoc.org/lua-filters.html
 
-main :: IO ()
-main = toJSONFilter doInclude
 local function words(s)
     local res = {}
     for part in s:gmatch("[^,]+") do                -- split by commas