Adjust the initial shebang line as appropriate to point to your local Lua interpreter.

#!/opt/local/bin/lua
--
-- l2y -- Extract data from a Lua file as YAML
--
-- $Id$
--

--
-- {{{ Map of data type to dump function
--
Dumpers = {
   ["table"] = function ( t, indent )
                  indent = indent + 2;
                  for k, v in pairs( t ) do
                     local keyname = cleanup_str( k );
                     io.write( prefix(indent) .. keyname .. ": " );
                     if type( v ) == 'table' then
                        io.write( "\n" );
                     end
                     do_dump( v, indent );
                  end
               end,
   ["string"] = function ( s, indent )
                   local outstr = cleanup_str( s )

                   io.write( prefix( indent ), outstr, "\n" );
                end,
   ["number"] = function ( n, indent )
                   io.write( prefix( indent ), tostring( n ), "\n" );
                end,
   ["boolean"] = function ( b, indent )
                    local val;
                    if b then
                       val = "true";
                    else
                       val = "false";
                    end
                    io.write( prefix( indent ), val, "\n" );
                 end,
   ["unknown"] = function ( u, indent )
                    io.write( "## Don't know how to dump type:",
                              type( u ), "\n" );
                    io.write( prefix( indent ), "~\n" );
                 end,
}
--
-- }}}
--

-- {{{ cleanup_str -- if s contains any "funny" chars spit out a quote
+d
--                    version instead
function cleanup_str( s )
   local outstr = s;

   if string.find( outstr, "[^%w]" ) then
      outstr = string.gsub( string.format( "%q", s ), "\\\n", "\\n" );
      outstr = string.gsub( outstr, "\r", "" );
   end

   return outstr
end
--
-- }}}
--

function prefix( indent ) return string.rep( " ", indent ); end

function do_dump( val, indent )
   local d = Dumpers[ type( val ) ];
   if d then
      d( val, indent );
   else
      Dumpers[ "unknown" ]( val, indent );
   end
end

if arg["n"] < 2 then
   io.write("usage: ", arg[0], " filename VarName [VarName...]\n" );
   os.exit( 1 );
end

local file = arg[1]
assert(loadfile(file))()

local fenv = getfenv( 1 );

io.write( "--- #YAML:1.0\n" );

for i = 2, arg["n"] do
   local cur = arg[ i ];
   local val = fenv[ cur ];

   if val then
     io.write( "## ", tostring(cur), " val: ", tostring(val), "\n" );
     io.write( tostring(cur), ":\n" );
     do_dump( val, 0 );
   else
           io.write( "## ", tostring(cur), " nil???\n" )
                 io.write( tostring(cur), ": ~\n" ); 
   end
end

os.exit( 0 );
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