RDF Data Model

Implementation status (2026-07-23, kelly): ✅ Implemented (a stale Language-Tags section was corrected in this commit). The capability is shipped: ingest_rdf / export_rdf for all 6 formats (Turtle, N-Triples, N-Quads, RDF/XML, JSON-LD, TriG) via oxrdfio, blank-node round-trip, and XSD→Value mapping (src/rdf.rs, src/types.rs). Drift (corrected in this commit): the “Language Tags” section (and its type-mapping row) is OBSOLETE — it claims rdf:langString is stored as Value::Str("text@lang") and re-split on @, but the code uses a dedicated Value::Lang { lexical, lang } variant (src/types.rs, tag 6); reconstructing a lang tag by splitting a Str on @ was a fixed bug. The Language Tags section + type-map row are now corrected to match.

Quipu bridges standard RDF types with the EAVT fact log via the rdf module. This layer handles conversion between oxrdf types and the integer-encoded term dictionary.

Type Mapping

RDF terms map to Quipu’s Value type based on XSD datatype:

Ingestion

Parse any RDF format and write to the fact log in a single transaction:

#![allow(unused)]
fn main() {
use quipu::{Store, ingest_rdf};
use oxrdfio::RdfFormat;

let mut store = Store::open_in_memory().unwrap();
let turtle = r#"
@prefix ex: <http://example.org/> .
ex:alice ex:name "Alice" ; ex:age "30"^^xsd:integer .
"#;

let (tx_id, count) = ingest_rdf(
    &mut store,
    turtle.as_bytes(),
    RdfFormat::Turtle,
    None,                          // base IRI
    "2026-04-04T00:00:00Z",       // timestamp
    Some("crew/braino"),           // actor
    Some("entity-file.ttl"),       // source
).unwrap();
// tx_id: transaction ID, count: 2 triples ingested
}

Supported formats: Turtle, N-Triples, N-Quads, RDF/XML, JSON-LD, TriG.

Export

Serialize current facts back to any RDF format:

#![allow(unused)]
fn main() {
use quipu::export_rdf;
use oxrdfio::RdfFormat;

let ntriples = export_rdf(&store, RdfFormat::NTriples).unwrap();
let turtle = export_rdf(&store, RdfFormat::Turtle).unwrap();
}

Blank Nodes

Blank nodes are stored in the term dictionary with a _: prefix. They round-trip correctly through ingestion and export.

Language Tags

Language-tagged literals (rdf:langString) are stored as a dedicated Value::Lang { lexical, lang } variant — the lexical form ("hello") and the language tag ("en") held in separate fields, never concatenated. On export the tag is reattached from the lang field. (A previous design concatenated them as "text@lang" in a Value::Str and re-split on @; that is a fixed bug — a lexical form may legitimately contain @, so the tag lives in its own field.) Datatyped literals with a non-standard ^^<datatype> use the parallel Value::Typed { lexical, datatype }, preserving the lexical form byte-for-byte.