Malte UblandClaude Opus 5.5 2ae1f72d0b Read self-capturing closures through selfRef instead of their box
`const visit = (node) => { ... visit(child) ... }` lowered to a closure
over the box of `visit`, and the box then held the closure: a two-object
reference cycle that only the cycle collector could free, along with
everything the closure captured. Nested function declarations already
read their own name through selfRef; arrows and function expressions
stored into a binding now do too, when the IR proves the binding holds
the closure itself whenever the closure can run.

resolveSelfCaptures runs with the other backend IR passes, before
copyStableCaptures. A capture qualifies when every creation site stores
the new closure, unadapted and with the binding's own type, into a boxed
local of the creating function (its only declaration's initializer, or
the only assignment after an empty declaration in the same statement
list), nothing else writes the binding in any body that shares its box,
and the closure body is synchronous, not a generator, and does not hand
the binding to a nested closure. The capture then leaves the body and
every creation site; its reads become selfRef. A creating binding that
no other closure captures loses its box, except dead-zone bindings.

Self-hosted compiler (native, compiling its CLI to IR): the cycle
collector frees 14.5M objects instead of 22.1M; closures that held a box
containing themselves drop from 3.5M to 54k. Of the runtime suite and the
cg-* cycle workloads, only published-graphs compiles differently
(-1.3%, 31 interleaved runs).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-18 11:50:59 -07:00
2026-10-16 10:33:14 -05:00
2026-10-14 17:27:02 -05:00
2026-10-17 13:47:41 -05:00
2026-07-22 18:08:04 -05:00
2026-07-22 18:08:04 -05:00

scriptc

Vercel Labs Experiment npm version: scriptc License: Apache-2.0 npm downloads per month: 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

Contributing

See CONTRIBUTING.md for source setup, testing, native artifact builds, and docs development.

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