XSLTn

XSLTn is a proposed extension to the Extensible Stylesheet Language Transformations (XSLT) designed to address modern data workflows by combining streaming processing with a richer type and module system. It aims to transform XML documents efficiently in streaming pipelines and to improve interoperability with JSON and other data formats.

Origin and status: XSLTn emerged in the 2020s as an open discussion among developers seeking to adapt XSLT for real-time data integration and large-scale processing. As of 2025, it is not an official standard; no W3C recommendation exists, and only experimental implementations and research prototypes are publicly documented.

Key features: Streaming templates and incremental evaluation enable transformations without loading entire documents into memory. A schema-aware type system provides better validation and safer expressions. A modular packaging model with imports and namespaces supports reuse across projects. Native support for JSON (and optional YAML) output, plus flexible serialization options, improves interoperability with contemporary data ecosystems. Higher-order templates, functional constructs, and extended path expressions enable more expressive transformation logic. Enhanced debugging, error reporting, and deterministic evaluation aid maintainability.

Syntax and approach: XSLTn preserves the template-based, pattern-matching style familiar to XSLT users but adds explicit typing, streaming annotations, and a module syntax. It remains XPath-inspired for navigation but extends it with type-checked expressions and streaming-friendly evaluation rules.

Relationship to XSLT: XSLTn is intended as a successor or alternative to traditional XSLT 2.0/3.0 approaches, not a backward-compatible replacement; transition would rely on tooling and compatibility layers.

See also: XSLT, XPath, XQuery, XML, JSON.