the language lacks a number of things:

  if/unless statements need to support ==, !=, >, <, etc.

  else/elsif support for if/unless statements

  print should let you index into an array

  helper functions for html/xml escaping output

  include/process directive, to pull in either files or templates

  ability to use quoted strings/literal numbers as args

the command line tool has a few other issues:

  should be able to define arrays and hashes from the command line

efficiency / correctness issues:

  we should read more than one line at a time when lexing

  we need to produce useful error messages not just return APR_EINVAL