Standard Object Types

This chapter forms an integral part of the language and its implementation is mandatory.

Dynamic Data Structure Types

[subr dict()] := {
  method __get__(k),
  method __set__(k, v),
  method __copy__(),
  method __final__(),
  method __unset__(k),
  method firstkey(),
  method nextkey(k),
}

The function dict creates a dictionary, also known as associative arraies, or hash table (from the implementation's perspective) in literatures. The semantics of __get__, __set__, __copy__, __final__, and __unset__ are as described in 9.2. Object/Value Key Access,

Before returning, dict shall initialize the dictionary with a method member with the name of __initset__ which is used for object definition notation. When this method is called with __proto__ as the first argument (discounting the this argument since it's a method), it shall remove itself from the dictionary.

Note: cxing conflates 2 usages for the dict type - first, as a data structure type holding unordered set of keyed values; second, to support the 'appearence' of so-called object-oriented programming. The second usage was set as part of the expressiveness goal for the language since its inception, the behavior of __initset__ is largely irrelevant for this usage. For the first usage however, it is undesirable that the __keys__ method enumerates __initset__, as one of the results. Hence the new 2026-03-12 requirement for the default implementation of __initset__ to unset itself.

There is an undefined order of all keys in the dictionary which is relevant for discussion the cardinarlity of the set of keys in a dictionary. The firstkey and the nextkey methods can be used to iterate over the keys in a dictionary:

• When firstkey method is called, it returns the key that is ordered before all other keys.
• When the nextkey called with a key that is present in the dictionary, it returns the key that is ordered adjacently next to the called key from the argument. In particular, if the called key is ordered after all keys present in the dictionary, null is returned. The keys corresponding to type-associated properties are not returned.

Note: The firstkey and the nextkey method replaces the earlier snapshot technique for enumerating dictionary keys, as the latter suffers from high memory usage with large dictionaries.

Type Reflection

subr isnull(x);
subr islong(x);
subr isulong(x);
subr isdouble(x);
subr _Uncast(x);

The functions isnull, islong, isulong, isdouble, determines whether the value is the special value null, of type long, type ulong, or type double respectively.

The function _Uncast performs uncasting of nulls - an operation whose semantic is described in 10. Types and Special Values.

TODO 2025-12-26: decide what to do with non-null arguments for uncasting. Idea 2026-04-19: uncast to 0. most POSIX API calls return 0 on success and -1 on error. Since most of the use of blessed nulls are to report errno codes, which are non-zero, this sort-of makes sense.