What is NOT a builtin
Compiler virtual modules cover systems I/O, threads, env, FFI, and IEEE float math. Collections, text/bytes helpers, decimal parse, path, blocking IO adapters, whole-file helpers, regex, TLS, crypto, time, and HTTP are not HostInvoke/opcodes — they live in userland packages (coil-stdlib, coil-regex, coil-tls, coil-crypto, coil-time, …).
Still not a compiler builtin (and not coil-stdlib either):
| Category | Examples | Where to look |
|---|---|---|
| Raw memory | alloc, free | gc::Root / gc::Weak |
| Regex | PCRE2 | coil-regex (regex) |
| TLS | rustls | coil-tls (tls) |
| Crypto | hashes, AEAD, keys | coil-crypto (crypto) |
| Time | calendar, monotonic Instant | coil-time (time) |
Use io for streams, FFI for C libraries, or host natives when embedding the VM in Rust.