# sestoft/C5

C5 generic collection library for C#/.NET

Repository: https://github.com/sestoft/C5
Canonical: https://ross.abutalabs.com/products/c5
Homepage: http://www.itu.dk/research/c5/
Language: C#
License: MIT
License Family: permissive
Last push: 2024-09-05T18:33:12+00:00

## Health v2 (maintenance only)
Score: 23/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 5619, "days_push": 727, "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 1068, forks 177 (observed 2026-08-28T04:03:27.385104+00:00)

## What it is
C5 is a generic collection library for C# and other .NET/CLI languages, providing a wide range of classic data structures such as lists, sets, bags, dictionaries, priority queues, and updatable views. It emphasizes rich functionality, orthogonal interfaces, documented asymptotic performance, and a thoroughly tested implementation.

## Use cases
- need advanced data structures like priority queues or tree dictionaries in C#
- want richer collection functionality than System.Collections.Generic
- require updatable views or snapshots of collections
- need guaranteed asymptotic time complexity for collection operations
- looking for a well-tested alternative collection library for .NET
- want a common interface across list-like collection implementations

## When to choose
- you need data structures or advanced features (views, snapshots, priority queue handles) missing from the standard .NET collections
- you care about documented performance guarantees and orthogonality of collection interfaces
- you work in C#, F#, or VB.NET on modern .NET runtimes

## When to avoid
- your needs are fully covered by System.Collections.Generic
- you want a library with frequent updates and a large active community
- you target platforms without generics-enabled .NET runtime support

## Facets
- artifact type: library
- maturity: maintenance
- function: developer-tools
- domain: developer-tools, programming-languages
- platform: dotnet, cross-platform
- tags: collections, data-structures, csharp, generic-collections, priority-queue, algorithms

## Member repositories
- sestoft/C5 (main) score 23

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:27.385104+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 2026-08-30T06:55:02.883794+00:00, confidence not recorded.
  - readme: https://github.com/sestoft/C5 (fetched 2026-08-28T04:03:27.385104+00:00, sha 53943597c56d)
- Data as of 2026-08-30T08:39:29.467469+00:00.