# Platform Notes

> USearch for Rust

### What This Binding Does Not Expose

These C entry points also take a deferred completion, but the crate calls them blocking, whatever receiver you hold:

- The `load_*` family, `view_nvme`, `metadata` and `metadata_buffer`, with each load config's `executor` choosing where it fans out.
- `clear`, which runs on the calling thread under `&mut DenseIndex`.
- Cursor and search-stream pulls, which run on the executor of the receiver that opened them, and open only from a blocking one.

`init_ram`, `init_vram` and `view_ram` block in C as well.

### Design

- __A thin layer over the C ABI.__
  Every name follows `c/usearch/`: a C verb `usearch_dense_<verb>` is a `<verb>` here, each module mirrors one header, a verb's argument struct becomes its `Dense*Config`, and every wrapper's documentation names the C symbol it calls.
  Enums mirror C enums, never strings.
- __The receiver chooses, the verb stays.__
  `&DenseIndex` runs a verb on the calling thread, `on(&executor)` blocks on an executor, and `deferred(&executor)` submits it, all with the same arguments.
- __Deferred calls use the language's own idioms.__
  `status` polls through `usearch_outcome_status`, `wait` blocks through `usearch_outcome_wait`, and a `Deferred` is `IntoFuture`, so `.await` polls the status word, since the library has no wake-up.
- __No life of its own.__
  The binding starts no threads and keeps no queues; releasing a `Deferred` rides `Drop`, which waits for the call first.
- __Arenas are lent and reused, never shared.__
  Every output whose length scales with the call lands in an arena the caller passes; the result borrows it, so the borrow checker retires stale views at compile time.
- __Nothing costs anything until it is used.__
  Blocking calls allocate no box, and an arena allocates only when a call writes into it.
- __Callers lend memory, never an allocator.__
  No allocation callback crosses into the library: payload belongs to the index, placed by its constructor's residency, and scratch belongs to the executor.
- __A deferred receiver refuses borrowed inputs at compile time.__
  The `Accepts` bound admits only owned inputs, so a borrow the library would read after the verb returns never compiles.