zamlit

Zamlit is a declarative data description language and templating engine designed to describe, validate, and transform structured data for software systems. It combines a compact, human-readable syntax with an extensible runtime that can generate code, validate input, and serialize outputs in multiple formats.

Design goals include readability, predictable schema evolution, and interoperability with existing data formats such as JSON, YAML, and XML. Zamlit uses schemas to define data shapes, including primitive types, composite structures, enumerations, and optionality, along with constraints and default values.

Key features include strong typing, declarative templates, data validation, and modular reuse through imports and libraries. It supports transformations via embedded expressions and mapping rules that convert between Zamlit structures and target formats or languages.

Typical use cases are API contract definitions, configuration management, data migration tasks, and templated data generation for tests and documentation. It is designed to be tool-agnostic, with parsers and code generators available for several programming languages. While any schema language has its limitations, Zamlit is described in various community discussions as a flexible alternative to ad hoc JSON schemas, though it remains less mainstream than some established formats. Related concepts include JSON Schema, YAML, XML, Protocol Buffers, Thrift, and GraphQL.