lihaoyi/Metascala

Health v2 · maintenance only

Flags: no_releases no_license

Adoption not part of the score

1185 stars · 95 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

Metascala is a tiny metacircular Java Virtual Machine written in about 3000 lines of Scala, including a bytecode interpreter, a stack-machine to SSA register-machine translator, a custom heap with a copying garbage collector, and partial JNI support. It runs on a host JVM and is intended as an approachable platform for experimenting with JVM features and running untrusted bytecode in a virtualized sandbox.

Use cases

• experiment with JVM internals without reading HotSpot's million lines of C++
• run untrusted Java bytecode in a sandboxed interpreter
• implement experimental language features like continuations or value types on the JVM
• learn how a virtual machine, heap, and garbage collector work
• translate stack-machine bytecode to SSA register-machine form

When to choose

• you want a small, readable JVM codebase to study or modify
• you need a research playground for VM-level experiments like continuations or isolates
• you want to safely interpret untrusted bytecode with virtualized memory and CPU usage

When to avoid

• you need a production-grade, high-performance JVM
• you require full JVM compatibility or up-to-date Scala support
• you need maintained software with an explicit license

Facets

library · maturity maintenance

interpreter compiler security programming-languages compilers security jvm jvm metacircular-interpreter bytecode garbage-collector research sandboxing virtualization

Member repositories

For agents

markdown · JSON · MCP: product_card(name="lihaoyi/Metascala")