I think I may have figured it out

index.html

@@ -1,4 +1,4 @@
-$render{"lexer-test"}
+$render{"test"}
 
 $render{"templates/wares"}
 

pygments.lua

@@ -0,0 +1,12 @@
+function CodeBlock(block)
+  if block.classes[1] == "moon" then
+    local fname = os.tmpname()
+    local handle = io.open(fname, "w")
+    handle:write(block.text)
+    handle:close()
+
+    local p = io.popen(string.format("pygmentize -f html -l moonscript.py %s -x", fname))
+    local out = p:read("*a")
+    return pandoc.RawBlock("html", out)
+  end
+end

renderers/markdown.moon

@@ -19,7 +19,18 @@ convert = =>
   (md_source) ->
     filename = os.tmpname!
     write_exec md_source, @cmd, filename
-    Path.read_file filename
+    a = Path.read_file filename
+    require("moon").p a
+    a
+
+    -- fname = os.tmpname!
+    -- with io.open fname, "w"
+    --   \write md_source
+    --   \close!
+    --
+    -- p = io.popen (@cmd)\format lang, fname
+    -- out = p\read"*a"
+    -- out
 
 -- config command like this in site.moon:
 -- require("renderers.markdown").cmd = "pandoc --mathjax >"
@@ -28,7 +39,11 @@ class PandocRenderer extends require "sitegen.renderers.markdown"
   escape_cosmo = @escape_cosmo
   pandoc = convert @
 
-  cmd: "pandoc >"
+  -- cmd: "pandoc >"
+  cmd: "pandoc --mathjax --lua-filter pygments.lua >"
+  -- cmd: "pygmentize -f html -l %s %s"
+  -- cmd: "pygmentize -f html -l %s %s -x"
+  -- cmd: "pygmentize -f html -l moonscript.py test.moon -x -o lexer-test.html"
 
   render: (page, md_source) =>
     md_source = page\pipe "renderer.markdown.pre_render", md_source

site.moon

@@ -1,6 +1,7 @@
 sitegen = require "sitegen"
 Site = require "sitegen.site"
 Path = require "sitegen.path"
+PygmentsPlugin = require "sitegen.plugins.pygments"
 html = require "sitegen.html"
 common = require "sitegen.common"
 cosmo = require "sitegen.cosmo"
@@ -13,17 +14,40 @@ import p from require "moon" -- debug
 -- Change output dir to what Openresty prefers
 Site.config.out_dir = "html/"
 
+-- PygmentsPlugin.highlight = (lang, code) =>
+--   fname = os.tmpname!
+--   with io.open fname, "w"
+--     \write code
+--     \close!
+--
+--   p lang
+--
+--   -- p = io.popen ("pygmentize -f html -l %s %s")\format lang, fname
+--   p = io.popen ("pygmentize -f html -l moonscript.py %s -x")\format fname
+--   out = p\read"*a"
+--
+--   -- get rid of the div and pre inserted by pygments
+--   assert out\match('^<div class="highlight"><pre>(.-)\n?</pre></div>'),
+--     "Failed to parse pygmentize result, is pygments installed?"
+
+
+
 -- Configure the command our custom renderer uses to convert markdown to html
 rend = "renderers.markdown"
-require(rend).cmd = "pandoc --mathjax >"
+-- require(rend).cmd = "pandoc --mathjax --no-highlight >"
 -- require(rend).cmd = "pandoc --mathjax -f json >"
 
+-- require(rend).cmd = "pandoc --mathjax --no-highlight --lua-filter ./pygments.lua >"
+
 -- Insert custom renderer in the first position so it will be preferred
--- table.insert Site.default_renderers, 1, rend
+table.insert Site.default_renderers, 1, rend
 
 -- Remove "pygments" plugin because it conflicts with pandoc syntax highlighting
--- Site.default_plugins = for v in *Site.default_plugins
---   if v\find "pygments" then continue else v
+Site.default_plugins = for v in *Site.default_plugins
+  if v\find "pygments" then continue else v
+
+-- plugin = "plugins.pygments"
+-- table.insert Site.default_plugins, 1, plugin
 
 -- from https://github.com/leafo/sitegen/blob/v0.2/spec/sitegen_spec.moon#L9-L18
 get_files = (path, prefix=path) ->
@@ -118,8 +142,8 @@ sitegen.create =>
     } for path in *files
 
   add "index.html", title: "Catalin Mititiuc"
-  -- add "blog.html", title: "Posts", target: "posts/index", template: "blog"
-  -- add_all files_from "docs"
+  add "blog.html", title: "Posts", target: "posts/index", template: "blog"
+  add_all files_from "docs"
 
   -- replace post markdown yaml headers with moonscript headers
   filter "docs", (body) =>
@@ -128,6 +152,7 @@ sitegen.create =>
       moonscript_header = header\gsub "%.%.%.", "}"
       moonscript_header
 
+  copy "moonscript.py"
+  copy "pygments.lua"
   copy "app.css"
-  -- copy "pygments.css"
   copy "moonscript.css"

test.md

@@ -0,0 +1,28 @@
+```elixir
+if config_env() != :prod do
+  # Configure pandoc (the version is required)
+  config :pandoc,
+    version: "3.6.1",
+    hello: [
+      args: fn extra_args ->
+        {_, [input_file], _} = OptionParser.parse(extra_args, switches: [])
+        ~w(--output=../priv/static/posts/#{Path.rootname(input_file)}.html)
+      end,
+      cd: Path.expand("../documents", __DIR__)
+    ]
+end
+```
+
+**this is a string!!**
+
+```moon
+class Thing
+  name: "unknown"
+
+class Person extends Thing
+  say_name: => print "Hel#lo, I am #{@name}!"
+
+with Person!
+  .name = "MoonScript"
+  \say_name!
+```

test.moon

@@ -1,9 +0,0 @@
-class Thing
-  name: "unknown"
-
-class Person extends Thing
-  say_name: => print "Hel#lo, I am #{@name}!"
-
-with Person!
-  .name = "MoonScript"
-  \say_name!