# `Volt.Builder.Declarations`
[🔗](https://github.com/elixir-volt/volt/blob/v0.23.0/lib/volt/builder/declarations.ex#L1)

Writes the type declarations of a library entry as one `.d.ts`.

Each TypeScript module of the entry's graph is emitted through OXC's isolated
declarations, which need explicit types on exported declarations and report
the ones they cannot infer; a plugin-owned module, such as a `.vue` file, is
declared by its plugin. The declarations are then bundled the way
`rollup-plugin-dts` bundles them: the graph is walked from the entry along
the declarations' own imports, so modules that only hold types are included;
only the declarations the entry's exports reach are kept, along with ambient
declarations such as `declare module`; imports of other packages are hoisted
and merged; and two modules declaring the same name are told apart by
renaming the one further from the entry.

Declarations are module-scoped, so names resolve at the top level of each
module: an identifier is the module's own declaration of that name, or what
the module imports under that name. Property names, type parameters and
parameters are left alone.

# `bundle`

```elixir
@spec bundle(Path.t(), Volt.Builder.Context.t()) ::
  {:ok, String.t()} | {:error, term()}
```

Bundle the declarations of the module at `entry` into one `.d.ts` source.

Returns `{:error, {:declarations, path, reason}}` when a module's declarations
cannot be emitted (`reason` is then the emitter's diagnostics) or hold a
construct the bundler does not handle (`reason` is then a message).

---

*Consult [api-reference.md](api-reference.md) for complete listing*