# hylo-lang/hylo

The Hylo programming language

Repository: https://github.com/hylo-lang/hylo
Canonical: https://ross.abutalabs.com/products/hylo
Homepage: https://www.hylo-lang.org
Language: Swift
License: Apache-2.0
License Family: permissive
Topics: programming-language
Last push: 2026-08-24T21:04:06+00:00

## Health v2 (maintenance only)
Score: 83/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 52, longevity 100
- inputs: {"age_days": 2047, "days_push": 9, "days_rel": 111, "gap_med": null, "n_releases_24m": 1}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1551, forks 64 (observed 2026-08-28T04:05:02.219281+00:00)

## What it is
Hylo (formerly Val) is a systems programming language built around mutable value semantics and generic programming, implemented in Swift with LLVM. This repository contains the former compiler implementation, with active development having moved to the hylo-lang/hylo-new repository.

## Use cases
- compile programs written in the Hylo language
- experiment with mutable value semantics in a systems language
- study compiler implementation using Swift and LLVM
- contribute to programming language research
- explore generic programming language design
- build a language toolchain from source with CMake or Swift Package Manager

## When to choose
- you want to experiment with or research value-semantics-based language design
- you want to contribute to compiler development or PL research
- you need to build or test the legacy Hylo compiler toolchain

## When to avoid
- you need a production-ready language for shipping software
- you want the current Hylo compiler, which is developed in hylo-lang/hylo-new
- you need mature tooling, debuggers, or ecosystem support

## Facets
- artifact type: cli-tool
- maturity: active
- function: compiler, programming-language, developer-tools
- domain: programming-languages, compilers, developer-tools
- platform: windows, cpp
- tags: value-semantics, generic-programming, systems-programming, llvm, language-implementation, research-language, macos, linux, swift

## Member repositories
- hylo-lang/hylo (main) score 83

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:02.219281+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 2026-08-30T04:30:15.966947+00:00, confidence not recorded.
  - readme: https://github.com/hylo-lang/hylo (fetched 2026-08-28T04:05:02.219281+00:00, sha 60333ce4e5aa)
  - homepage: https://www.hylo-lang.org (fetched 2026-08-29T11:30:50.668591+00:00, sha d7b98fbe123d)
  - site_page: https://hylo-lang.org/docs/contributing/research-collab (fetched 2026-08-29T11:30:50.682212+00:00, sha 8d5da048e7a9)
  - site_page: https://hylo-lang.org/docs/contributing/community (fetched 2026-08-29T11:30:50.678030+00:00, sha 57da890a7295)
  - site_page: https://hylo-lang.org/docs (fetched 2026-08-29T11:30:50.680322+00:00, sha f22b11000fb5)
  - site_page: https://hylo-lang.org/docs/contributing (fetched 2026-08-29T11:30:50.684337+00:00, sha 48c1816f9c8b)
- Data as of 2026-08-30T08:39:29.467469+00:00.