# join

Constructs an ordered joined Route AST node.

## Signatures

```ts
export declare const join: (parts: ReadonlyArray<RouteAst>) => RouteAst.Join;
```

## Why

Nested route schemas and parameter ownership remain visible after composition.

## Ownership and lifetime

`join` returns a fresh plain AST node immediately and retains any supplied child nodes or arrays by reference; it acquires no external resource.