Nomenclature

This document establishes the formal vocabulary used throughout the KUMI library to ensure consistency across API documentation, error messages, and internal implementation details.

In the context of KUMI, a distinction is made between types as stored, types as accessed, and the metadata used to describe them.

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Element

An element is the fundamental constituent type of a heterogenous container. In literature, this corresponds to the Value Type ( \( T \)) stored within a node.

• Definition: The raw, decayed type provided during template instantiation.
• Example: In kumi::tuple<int, double>, the elements are int and double.

Member

A member is the functional result of a sub-object access operation, the result of a projection.

Formally, a member is an Element qualified by the value category of the container and the cv-qualifiers of the access path.

• Definition: The result of get<I>(container).
• Example: Given kumi::tuple<int> t, get<0>(t) yields the member int&, while get<0>(std::move(t)) yields int&&.

Identifier

An identifier is a compile-time constant or type used as a key to resolve a specific sub-object within a structure.

• Definition: A unique tag, integral constant, or symbolic name used for dispatching and name-binding.
• Role: It decouples the logical "address" of a value from its physical offset in memory.

Field

A field is the combination of an Identifier and its associated Element.

• Formal Logic: Let \( I \) be an Identifier and \( E \) be an Element. Then \( Field = \{I, E\} \).
• Role: Fields are used to define the schema of a tuple-like structure.

Label

A label is the external, human-readable representation (string-equivalent) associated with an Identifier or Field.

• Definition: The lexical name used for introspection, serialization, and diagnostic output.
• Note: While an Identifier is a programmatic entity (like a type or index), a Label is a literal value (typically a const char* or string_view), in kumi, there is a special type used to describe these : kumi::str.

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Summary Table

Concept	Formal Analogy	Domain	Example
Element	Value Type	Static Type	float
Member	Reference/Access Type	Invocation	float const&
Identifier	Key / Index	Metadata	"my_data"_id
Field	Schema Attribute	Reflection	{id, type} pair
Label	Symbolic Name	User Interface	"velocity"