Liststr

Liststr is a data structure and software library designed to unify list and string processing by representing a sequence as a single, flexible object that can behave both as a list of elements and as a sequence of characters. The design aims to reduce the overhead of converting between list and string representations while enabling efficient manipulation of mixed data and text-based data pipelines.

Core features include immutable default semantics with optional mutable views, zero-copy slicing, and a set of operations that work uniformly on both list-like and string-like interfaces. A Liststr instance supports indexing, iteration, and slicing like a Python list, and also provides character-level operations such as indexing by character, substring, and concatenation, as well as conversions to native lists or strings. The interface is designed to be language-agnostic, enabling cross-language interoperability while keeping a consistent API.

Implementation: Liststr is typically built as a rope-like structure that stores chunks of data and supports caching for common operations. This allows efficient operations on long sequences without copying data. It can be implemented across languages; existing implementations include variants in Python, JavaScript, and Rust, with the original specification published in academic and developer documentation in the mid-2010s.

Applications: used in data ingestion, text processing, tokenization, and serialization tasks where the boundary between lists and strings is fluid. It helps reduce boilerplate when parsing structured text into tokens or when assembling outputs from mixed-type sequences, offering a unified approach to sequential data manipulation.

See also: sequences, ropes, tokenization, serialization, immutable data structures.