# twitter/rsc

Experimental Scala compiler focused on compilation speed

Repository: https://github.com/twitter/rsc
Canonical: https://ross.abutalabs.com/products/rsc
Language: Scala
License: Apache-2.0
License Family: permissive
Last push: 2021-10-21T17:27:10+00:00

## Health v2 (maintenance only)
Score: 32/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 35, longevity 100
- inputs: {"age_days": 3303, "days_push": 1777, "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 1233, forks 48 (observed 2026-08-28T04:04:04.609344+00:00)

## What it is
Rsc (Reasonable Scala compiler) is an experimental reimplementation of the Scala compiler focused on compilation speed, developed by Twitter's Language Tools team. It aims to study the compilation-time cost of Scala features and inform performance improvements in official Scala compilers.

## Use cases
- compile Scala faster
- measure compilation overhead of Scala features
- research Scala compiler architecture
- experiment with a from-scratch Scala compiler
- identify a fast-compiling subset of Scala

## When to choose
- you are researching Scala compiler performance
- you want to study how Scala idioms affect compile times
- you need SemanticDB-based dependency loading experiments

## When to avoid
- you need a production Scala compiler with full compatibility
- you want new language features or type system improvements
- you need an actively maintained tool

## Facets
- artifact type: cli-tool
- maturity: abandoned
- function: compiler, developer-tools
- domain: compilers, programming-languages, performance, developer-tools
- platform: jvm, cross-platform
- tags: scala, compilation-speed, experimental-compiler, semanticdb, compiler

## Member repositories
- twitter/rsc (main) score 32

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:04.609344+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 2026-08-30T08:33:20.464462+00:00, confidence not recorded.
  - readme: https://github.com/twitter/rsc (fetched 2026-08-28T04:04:04.609344+00:00, sha ba13aee27b63)
- Data as of 2026-08-30T08:39:29.467469+00:00.