zinc-vm

The shared ZINC VM executor for fixpoint-linux — a single, high-throughput interpreter + moving generational GC consumed by the language stacks that run on the system.

A Zig 0.16 native library package. Exposes two modules:

• gc — the moving generational collector (src/gc.zig: types/heap/collect/scan/roots)
• vm — the ZINC interpreter + prims (src/vm.zig: state/values/symbols/tables/parser/interp/prims/streams/execplan/hostcall/marshal)

Consumers

• fx-ui — Elm → ZINC-csexp compiler + runtime (src/effectloop.zig is consumer-side)
• shen — the self-hosting Shen OS (shensh, zincdec)

Both consume this package via a build.zig.zon path dependency (later a git submodule / zig fetch).

The shared-executor consolidation

The org previously had two divergent copies of this VM (fx-ui's and shen's). This package is the single canonical source: fx-ui's newer base (M6–M11 perf: frame-stack pool, tail-env reuse, single-probe global lookup) reconciled with shen's eval-kl chain (marshal, catching hostcalls, wait/kill). Arithmetic prims deliberately carry no type guards (bare +%/-%/*%/@divTrunc semantics) — per AGENTS.md the metacircular interpreter relies on it and type errors belong to the safe-wrapper layer, not the VM.

Build & test

zig build            # library
zig build gate       # gc+vm tests in Debug/ReleaseSafe/ReleaseFast (3 × 138)
zig build test       # Debug tests

Repo conventions

• Native-only (no wasm target).
• build.zig exposes gc and vm via b.addModule for package consumers; per-mode gate instances use b.createModule (independent optimize).
• Commits follow conventional style (feat:/fix:/chore:/refactor:).