# `RustQ.Meta.Desugar`
[🔗](https://github.com/elixir-crab/rustq/blob/v1.0.0-rc.19/lib/rustq/meta/desugar.ex#L1)

Rewrites standard-library calls that are other Rusty-Elixir into that Rusty-Elixir, before
`RustQ.Meta.Ownership` and lowering see a body, so lowering keeps to forms Rust has:

  * `Map.new/1,2`, `MapSet.new/1,2`, and `Enum.into/2,3` into an empty collection are a
    comprehension collecting into it;
  * `Enum.group_by/2,3` is a map filled by a loop, and `Enum.uniq/1` and `Enum.uniq_by/2`
    keep the items a set has not seen;
  * a generator over `Enum.with_index(list)` enumerates the list in place.

Where a rewrite needs what only lowering knows, it leaves an internal form for lowering to
resolve: `__rustq_items__(list)` iterates a list as its ownership allows, and
`__rustq_owned__(item, list)` is an item of `list`, copied where that costs nothing and
cloned otherwise.

# `apply_function`

```elixir
@spec apply_function(Macro.t(), Macro.t()) :: Macro.t()
```

A one-argument function applied to `value`, inlined: `fn name -> name.len() end` applied to
`item` is `item.len()`, and `&key/1` applied to it is `key(item)`.

# `desugar`

```elixir
@spec desugar(Macro.t()) :: Macro.t()
```

Rewrites `body`'s standard-library calls that are other Rusty-Elixir.

---

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