# `Beaver.Pattern.Native`

An explicitly callback-backed rewrite DSL.

`defrewrite/3` binds selected pieces of an operation before running an
Elixir callback through `Beaver.MLIR.RewritePattern`. It does not build PDL
and never switches between the native and PDL execution engines.

A declaration generates a zero- and one-arity builder. For example,
`fold_add/0` returns a `Beaver.Pattern.Native.Descriptor`, while
`fold_add/1` can override lifecycle options such as `:benefit` and
`:init_state`.

# `defrewrite`
*macro* 

Defines a native rewrite and generates a descriptor builder.

The declaration must name the callback's operation, borrowed pattern
rewriter, and state arguments with three variables. Destructure state inside
the body when needed. `:root` is required. Optional `:operands`, `:results`,
and `:attributes` declarations are Elixir patterns; a mismatch returns
no-match without evaluating the body.

The body may return `:ok`, `:no_match`, `{:ok, new_state}`, or
`{:error, new_state}`.