# Platform Notes

> USearch for Python

### Tooling

`usearch.io` reads and writes the `fbin` / `ibin` / `i8bin` matrix formats, and `usearch.eval` carries the recall harness, which takes the index or any blocking receiver:

```python
from usearch.eval import self_recall

stats = self_recall(index.on(pool), usearch.Arena(pool))
print(stats.mean_recall, stats.mean_efficiency)
```

### What This Binding Does Not Expose

- `cursor` and `search_stream` on a `DeferredOn`: they open walks whose every pull blocks, so there is nothing to submit.
- `usearch_dense_metric_from_name`: `DenseMetric` is an `enum.IntEnum`, so `DenseMetric["ANGULAR"]` parses a name and no string ever reaches a verb.

### Design

- __A thin layer over the C ABI.__
  Every name follows `c/usearch/`: a C verb `usearch_dense_<verb>` is a `<verb>` here, a type drops `usearch_` and `_t`, and enums mirror C enums as `enum.IntEnum` classes, never strings.
- __The receiver chooses, the verb stays.__
  The index 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 `await` hands `wait()` to the running event loop's default executor.
- __No life of its own.__
  The binding starts no threads and keeps no queues; releasing a `Deferred` rides reference counting, 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; an exported buffer pins its arena until released, and a view over a rewound one raises `UninitializedError`.
- __Nothing costs anything until it is used.__
  Submitting a call allocates nothing, and an arena allocates only when a call writes into it.
- __Blocking calls stay as simple as the language allows.__
  `index.search(queries, 10, arena)` takes no executor, completion or receiver argument and returns its result; nothing about asynchrony reaches a caller who never asks for it.
- __Language idioms over parallel APIs.__
  The buffer protocol, `in`, struct sequences, context managers and `+=` take the place of helper methods, and `describe`, `health` and `metadata_read` answer the C structs as struct sequences, never as dicts.