# lacuna/bifurcan

functional, durable data structures

Repository: https://github.com/lacuna/bifurcan
Canonical: https://ross.abutalabs.com/products/bifurcan
Language: Java
License: MIT
License Family: permissive
Last push: 2025-12-30T22:26:21+00:00

## Health v2 (maintenance only)
Score: 59/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 59, release rhythm 35, longevity 100
- inputs: {"age_days": 3691, "days_push": 246, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1017, forks 55 (observed 2026-08-28T04:03:14.647347+00:00)

## What it is
Bifurcan is a Java library providing high-performance mutable and immutable (functional) data structures such as lists, maps, and sets with a common API. It offers efficient random access, inverted indices, splitting/merging, and fast batch set operations compared to standard java.util collections.

## Use cases
- use immutable persistent collections in Java
- faster hash map iteration than HashMap
- efficient union, intersection, and difference of collections
- custom equality and hash semantics for collections
- functional-style collection updates returning new collections
- convert collections to read-only java.util interfaces

## When to choose
- you need immutable or mutable data structures with better performance than java.util
- your workload relies heavily on batch set operations like merge or union
- you want deterministic memory layout for fast equality checks

## When to avoid
- you only need simple collections and are happy with java.util
- you need collections that implement java.util interfaces natively
- you work outside the JVM

## Facets
- artifact type: library
- maturity: active
- function: serialization
- domain: developer-tools, programming-languages
- platform: jvm
- tags: data-structures, immutable-collections, persistent-data-structures, functional-programming, jvm, algorithms

## Member repositories
- lacuna/bifurcan (main) score 59

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:14.647347+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T07:11:13.388232+00:00, confidence not recorded.
  - readme: https://github.com/lacuna/bifurcan (fetched 2026-08-28T04:03:14.647347+00:00, sha 1eceb3bbea8a)
- Data as of 2026-08-30T08:39:29.467469+00:00.