orderedCollection

orderedCollection is a data structure concept that describes a collection which preserves the sequence of its elements in the order they are inserted or arranged. It supports iterating over elements in that stored order and typically provides indexed access by position. The defining feature is determinism of iteration order, which makes the sequence predictable for processing and display.

Key characteristics of an ordered collection include the potential for duplicate elements, stable order during standard operations, and support for common mutating operations such as insert, remove, and access by index. Implementations vary across languages and libraries; common forms include dynamic arrays (lists) that offer fast random access and amortized appends, as well as linked structures that excel at insertions and deletions at arbitrary positions but may incur slower index-based access. Some environments provide deques or other sequence types that maintain insertion order with efficient front and back operations.

Ordered collections are often contrasted with unordered collections, such as sets, where iteration order is not guaranteed. They also differ from maps or dictionaries, where the primary structure is key-value pairs and the iteration order may depend on language-specific rules rather than the position of elements within the collection.

Common use cases for ordered collections include scenarios where the order of elements matters for display, serialization, or reproducible processing. They are integral in user interfaces, data pipelines, and any context where a stable, position-based sequence is required.

Related concepts include lists, arrays, vectors, and general sequences in various programming environments, as well as specialized variants like ordered sets or ordered maps that preserve order under additional constraints.