function(ast_parse stream definition_id )

  #message(PUSH)
  if(ARGN)
      set(args ${ARGN})
      list_pop_front( args)
      ans(ast_language)

      map_get(${ast_language}  parsers)
      ans(ast_parsers)
      map_get(${ast_language}  definitions)
      ans(ast_definitions)
      function_import_table(${ast_parsers} __ast_call_parser)

#      json_print(${ast_definitions})
  else()
      if(NOT ast_language)
          message(FATAL_ERROR "missing ast_language")
      endif()
  endif()

 # map_get(${ast_language} parsers parsers)
  map_get("${ast_definitions}"  "${definition_id}")
  ans(definition)
 
  map_tryget(${definition}  node)
  ans(create_node)
  map_get(${definition}  parser)  
  ans(parser)
  map_get(${ast_parsers}  "${parser}")
  ans(parser_command)
  map_tryget(${definition}  peek)
  ans(peek)

  #message("trying to parse ${definition_id} with ${parser} parser")
  if(peek)
    token_stream_push(${stream})
  endif()  
  #eval("${parser_command}(\"${definition}\" \"${stream}\" \"${create_node}\")")

  __ast_call_parser("${parser}" "${definition}" "${stream}" "${create_node}")
  ans(node)
  if(peek)
    token_stream_pop(${stream})
  endif()
 
 #if(node)
 #  message(FORMAT "parsed {node.types}")
 #else()
 #  message("failed to parse ${definition_id}")
 #endif()
 #  message(POP)
  return_ref(node)
endfunction()