namespace trial {
  namespace dynamic {
    template<template< typename > class Allocator> struct basic_array;
    template<template< typename > class Allocator> struct basic_map;

    template<template< typename > class Allocator> class basic_variable;

    struct boolean;
    struct integer;
    struct real;
    struct string;
    struct u16string;
    struct u32string;
    struct wstring;

    enum nullable { null };

    typedef basic_variable< std::allocator > variable;
    typedef basic_array< std::allocator > array;
    typedef basic_map< std::allocator > map;
    template<template< typename > class Allocator, typename U> 
      basic_variable< Allocator > 
      operator+(const basic_variable< Allocator > &, const U &);
    template<template< typename > class Allocator> 
      basic_variable< Allocator > 
      operator+(nullable, const basic_variable< Allocator > &);
    template<typename T, typename U> bool operator==(const T &, const U &);
    template<typename T, typename U> bool operator!=(const T &, const U &);
    template<typename T, typename U> bool operator<(const T &, const U &);
    template<template< typename > class Allocator, typename U> 
      bool operator<=(const basic_variable< Allocator > &, const U &);
    template<template< typename > class Allocator, typename U> 
      bool operator>(const basic_variable< Allocator > &, const U &);
    template<template< typename > class Allocator, typename U> 
      bool operator>=(const basic_variable< Allocator > &, const U &);
  }
}