derive-ocaml - Custom derive and procedural macros for easier ocaml <-> rust FFI

WARNING this crate is very experimental

derive-ocaml is based on top of ocaml-rs and adds a custom derive macro for FromValue and ToValue. The macro supports structs, enums, and unboxed float records.

On top of that it implemens a nightly only procesdural macro ocaml-ffi to ease the boilerplate of writing stubs functions.

```

[derive(Debug, Default, ToValue, FromValue)]

[ocaml(floats_array)]

pub struct Vec3 { x: f32, y: f32, z: f32, }

[ocaml_ffi]

pub fn rustaddvecs(l: Vec3, r: Vec3) -> Vec3 { l + r } ```

see src/example/src/lib.rs and src/example/src/stubs.ml for example