concept-graph

The materialized hierarchy of a code system.

Integer-keyed compressed sparse row adjacency for a code system's is-a hierarchy and each typed relationship, plus roaring transitive-closure bitmaps. Subsumption is a bitmap membership test, and the ECL evaluator compiles constraints to set algebra over these bitmaps. The graph is built offline by a loader and served read-only; no request traverses edges live. No FHIR or SNOMED specification governs the layout: it is this project's own design.

Where it sits

concept-graph is one crate of FerroTERM, a pure-Rust FHIR terminology server for SNOMED CT, LOINC, and other clinical code systems. The crates are published so other projects can reuse them; the API is pre-1.0 and moves with the FerroTERM release train. Documentation: https://docs.rs/concept-graph.

Licence

Business Source License 1.1 (LICENSE): free to read, build, modify, and redistribute, free for non-production use and for non-commercial production use; commercial production use needs a licence from the Licensor; each version becomes Apache License 2.0 four years after it is published. Clinical terminology content (SNOMED CT, LOINC, RxNorm, ICD, the Dutch national code systems) is licensed by its publisher and is never part of this crate.