spawn

See REFERENCE.md for the complete language reference.

spawn is a language builtin (like make, append). No import required. Patched into Go's type universe via build/patch-gotypes.go.

done := spawn(funcName, arg1, arg2, ...)
done := spawn("local", funcName, arg1, arg2, ...)  // explicit transport

Creates a new domain — an isolated OS process (native) or Worker (JS) — running funcName(arg1, arg2, ...) with its own cooperative scheduler and heap. Returns chan struct{} (lifecycle channel).

Codec Requirement

All data arguments and channel element types must implement moxie.Codec:

import "moxie"

type Codec interface {
    EncodeTo(w io.Writer) error
    DecodeFrom(r io.Reader) error
}

Built-in codec types encode little-endian by default. Big-endian aliases exist for protocols like Bitcoin:

Default (LE)	Big-endian (BE)	Size
moxie.Bool, moxie.Int8, moxie.Uint8	—	1 byte
moxie.Int16, moxie.Uint16	moxie.BigInt16, moxie.BigUint16	2 bytes
moxie.Int32, moxie.Uint32	moxie.BigInt32, moxie.BigUint32	4 bytes
moxie.Int64, moxie.Uint64	moxie.BigInt64, moxie.BigUint64	8 bytes
moxie.Float32	moxie.BigFloat32	4 bytes
moxie.Float64	moxie.BigFloat64	8 bytes
moxie.Bytes	—	4-byte LE length prefix + data

User-defined structs implement Codec by defining EncodeTo/DecodeFrom methods that encode each field.

Example

import "moxie"

func worker(n moxie.Int32, scale moxie.Float64) {
    println(float64(n) * float64(scale))
}

func main() {
    spawn(worker, moxie.Int32(42), moxie.Float64(2.5))
}

Type Checking

The type checker (patched go/types) validates:

• First argument must be a function (or transport string + function)
• Result type is chan struct{}

The compiler's SSA validator additionally enforces:

• All data argument types implement moxie.Codec
• All channel element types implement moxie.Codec
• No interface{} values cross the boundary
• No pointers, functions, or nested channels
• Only unbuffered channels allowed

Move Semantics

Non-constant, non-channel values passed to spawn cannot be used afterward:

x := compute()
spawn(worker, x)
println(x)        // compile error: ownership moved to child

Native Implementation

socketpair() + fork(). Child gets COW copy of parent memory. Each domain has its own Boehm GC heap, run queue, and goroutine stacks.

JS Implementation

$rt.domain.spawn(async () => fn(args)). Slices spread-copied, maps Object.assign'd. Isolated microtask scheduler per domain.