# boostorg/hana

Your standard library for metaprogramming

Repository: https://github.com/boostorg/hana
Canonical: https://ross.abutalabs.com/products/hana
Homepage: http://boostorg.github.io/hana
Language: C++
License: BSL-1.0
License Family: other
Topics: hana, boost, cpp, metaprogramming, cpp14, cpp11, header-only
Last push: 2026-08-12T11:35:26+00:00

## Health v2 (maintenance only)
Score: 66/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 97, release rhythm 8, longevity 100
- inputs: {"age_days": 4491, "days_push": 21, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1852, forks 224 (observed 2026-08-28T04:05:44.479473+00:00)

## What it is
Boost.Hana is a header-only C++14 metaprogramming library providing a standard library for computations on both types and values, including heterogeneous sequences, algorithms, and compile-time introspection. It is part of Boost and requires no external dependencies.

## Use cases
- manipulate heterogeneous tuples at compile time in C++
- perform type-level computations with normal C++ syntax
- check expression validity without SFINAE tricks
- unroll loops at compile time
- introspect user-defined struct members
- replace MPL/Fusion-style metaprogramming with a modern API

## When to choose
- you need compile-time computations on types and values in C++14 or later
- you want a header-only, dependency-free metaprogramming library
- you want to unify value and type computations in one API

## When to avoid
- your codebase is limited to C++11-only compilers without full C++14 support
- you only need simple constexpr utilities that don't justify a metaprogramming library
- compile times are extremely critical and heavy template instantiation is unacceptable

## Facets
- artifact type: library
- maturity: stable
- function: serialization, developer-tools
- domain: programming-languages, developer-tools
- platform: cpp, cross-platform
- tags: metaprogramming, header-only, cpp14, cpp11, boost, compile-time, type-level-programming, constexpr, algorithms

## Member repositories
- boostorg/hana (main) score 66

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:44.479473+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 2026-08-30T03:16:52.468078+00:00, confidence not recorded.
  - readme: https://github.com/boostorg/hana (fetched 2026-08-28T04:05:44.479473+00:00, sha 94bdd504cb5b)
  - homepage: http://boostorg.github.io/hana (fetched 2026-08-29T10:55:57.527995+00:00, sha 28d3e72469c5)
- Data as of 2026-08-30T08:39:29.467469+00:00.