SCRIPTC_YOUNG_NURSERY=1 at compile time makes an executable allocate traced, program-owned class instances and records young and link the collector unit built with SCR_YIN (a runtime pack variant of scr_cycle.c; libraries never get it). The emitted constructor lists the object in a per-thread nursery and marks its header: generation SCR_CYC_YOUNG and its nursery index under the buffered bit, so every existing release path treats it as a buffered candidate (no call while it stays alive; scr_cyc_on_dead takes it out of the nursery at its death). A nursery collection (whenever 4096 young objects are live, at collection points, before full sweeps and limited passes) counts each young object's references from other young objects, marks from the objects whose count is below their reference count (referenced from outside the nursery: stacks, globals, older objects, runtime structures, FFI, fibers, coroutine frames), frees what stays unmarked, and gives up the dead set's outgoing edges after the teardowns. The counts are recomputed at every collection instead of maintained by a store barrier, so soundness rests only on the invariants trial deletion already needs. Survivors join trial deletion's nursery and outside roots become candidates; trial deletion walks young objects it reaches as nursery-level objects. Per-type admission statistics send types that do not die in young cycles back to trial deletion for a while. Publication takes young objects out of the nursery. The RC audit build checks nursery membership and counts at every collection. With the flag off, the compiler emits and links exactly what it did before (249 programs and the self-hosted compiler compared byte-identical). Measured with the flag on: cg-rings -38%, cg-pairs -27%, the runtime suite geomean -0.3% (published-graphs +3.4%), the self-hosted compiler neutral; shapes whose cycles go through arrays or closures (phase 2) pay without gaining. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
scriptc
scriptc compiles TypeScript and JavaScript to native executables and WebAssembly. It uses the types checked by the TypeScript compiler to generate machine code, and the output runs without Node.js installed. npm packages your program imports compile along with it. Code scriptc can't compile is reported at build time with a diagnostic and, where available, a rewrite hint.
scriptc is experimental and supports a subset of JavaScript, TypeScript, and Node.js APIs. Run scriptc coverage on an existing program to see how much of it compiles, and see the limitations and Node.js compatibility reference for details.
Installation
Install with Node.js 24 or later and npm:
$ npm install -g scriptc
The installed compiler runs natively on macOS, Linux, and Windows. Node.js is needed only to install it and to run WASI modules with scriptc run. Standalone compiler archives are also available from GitHub Releases.
Building executables requires a linker and the platform SDK or sysroot. See the quickstart for prerequisites and platform support for host requirements, cross-compilation, and WebAssembly.
Build a program
Create hello.ts:
const who = process.argv.length > 2 ? process.argv[2] : "world";
console.log(`hello, ${who}`);
scriptc run compiles the file and runs the result:
$ scriptc run hello.ts
hello, world
scriptc build writes an executable:
$ scriptc build hello.ts -o hello >/dev/null
$ ./hello scriptc
hello, scriptc
These examples use POSIX shell syntax. On Windows, build hello.exe and run it with .\hello.exe.
Use scriptc coverage hello.ts to check what compiles before you build. See coverage reports for details.
Use Node APIs
Supported Node APIs compile to the native runtime. For example, server.ts:
import { createServer } from "node:http";
const server = createServer((req, res) => {
res.setHeader("content-type", "application/json");
res.end(JSON.stringify({ path: req.url }));
});
server.listen(8080, () => {
console.log("listening on http://localhost:8080");
});
$ scriptc build server.ts -o server >/dev/null
$ ./server
listening on http://localhost:8080
Use npm packages
npm packages compile into the executable with your code, so it doesn't read node_modules at runtime.
Create cli.ts:
import pc from "picocolors";
console.log(pc.green("hello from scriptc"));
$ npm install picocolors
$ scriptc build cli.ts -o cli >/dev/null
$ ./cli
hello from scriptc
Package support is partial. See npm dependencies for which packages compile and how to check them.
Documentation
- Introduction: what scriptc is and what you can build.
- Quickstart: installation and your first executable.
- Coverage reports: check whether an existing program compiles.
- Platform support: cross-compilation and WebAssembly.
- CLI reference: commands, options, and output formats.
- Native program objects: use compiler output in external builds.
- Native FFI: call C ABI functions from compiled programs.
- WebAssembly modules: build and embed WASI modules.
- Examples: programs and integration examples in this repository.
Contributing
See CONTRIBUTING.md for source setup, testing, native artifact builds, and docs development.