# `VFS.Default`
[🔗](https://github.com/ivarvong/vfs/blob/v0.1.0/lib/vfs/default.ex#L1)

Fallback implementations of `VFS.Mountable` ops, composed from the
required primitives. Used by `VFS.Skeleton` to fill in defaults for
backends that don't override.

# `walk`

```elixir
@spec walk(VFS.Mountable.t(), VFS.Mountable.path(), keyword()) :: Enumerable.t()
```

Default `walk/3` — lazy, depth-first traversal composed from `stat/2` and
`readdir/2`. Returns a `Stream` of `{path, %VFS.Stat{}}` tuples.

Options:

  * `:max_depth`     — `:infinity` (default) or a non-neg integer
  * `:include_dirs`  — emit directory entries themselves (default `false`)

## Laziness contract

The traversal is fully lazy: `Stream.take/2` halts as soon as the
consumer has enough, and **the underlying `readdir/2` is consumed
one entry at a time**. This means:

  * Unbounded directories work. A backend whose `readdir/2` returns
    a `Stream` of arbitrary length (e.g. a paginated S3 lister, a
    virtual `/integers/N` namespace) composes correctly with
    `walk |> Stream.take(N)` — only the first N entries' worth of
    directory work is performed.
  * Deep trees work. The traversal is recursive but each recursion
    produces a `Stream`, so an infinite-depth tree is bounded by
    what the consumer takes.

## Errors

Errors during traversal (e.g. a `readdir` that fails because the
directory was deleted between calls) are silent — the offending
subtree is skipped and walk continues. Callers needing strict error
surfacing should `stat` the root first or compose their own walk.

Cache state populated during enumeration does not escape — see the
cache-eviction caveat in `VFS.Mountable`.

---

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