This topic documents the data format for Datomic datalog queries and rules. If you want to follow along at a REPL, most of the examples on this page work use the mbrainz-subset database and are in the Day of Datomic Cloud repository.

DF is a directed, labeled graph data format for representing information in the Web. This specification defines the syntax and semantics of the SPARQL query language for RDF. SPARQL can be used to express queries across diverse data sources, whether the data is stored natively as RDF or viewed as RDF via middleware. SPARQL contains capabilities for querying required and optional graph patterns along with their conjunctions and disjunctions. SPARQL also supports aggregation, subqueries, negation, creating values by expressions, extensible value testing, and constraining queries by source RDF graph. The results of SPARQL queries can be result sets or RDF graphs.

Getting started

The spec library (API docs) specifies the structure of data, validates or conforms it, and can generate data based on the spec.

Clojure is a dynamic language. Among other things this means that type annotations are not required for code to run. While Clojure has some support for type hints, they are not an enforcement mechanism, nor comprehensive, and are limited to communicating information to the compiler to aid in efficient code generation. Clojure gets runtime checking of a richer set of types by the JVM itself.

However it has always been a guiding principle of Clojure, widely valued and practiced by the community, to simply represent information as data. Thus important properties of Clojure systems are represented and conveyed by the shape and other predicative properties of the data, not captured or checked anywhere since the runtime types are indistinguishable heterogeneous maps and vectors.

Documentation strings can be used to communicate with human consumers, but they can’t be leveraged by programs or tests, i.e. they have minimal power. Users have turned to various libraries such as Schema and Herbert to get more powerful specifications.