Macro ocaml::caml_body

macro_rules! caml_body {
    (||, <$($local:ident),*>, $code:block) => { ... };
    (|$($param:ident),*|, @code $code:block) => { ... };
    (|$($param:ident),*|, <$($local:ident),*>, $code:block) => { ... };
}

Defines an OCaml FFI body, including any locals, as well as a return if provided; it is up to you to define the parameters.