Macro impl_to_ocaml_record

macro_rules! impl_to_ocaml_record {
    ($rust_typ:ty => $ocaml_typ:ident {
        $($field:ident : $ocaml_field_typ:ty $(=> $conv_expr:expr)?),+ $(,)?
    }) => { ... };
    ($both_typ:ident {
        $($t:tt)*
    }) => { ... };
}

Implements ToOCaml for mapping a Rust record into an OCaml record.

It is important that the order of the fields remains the same as in the OCaml type declaration.

Examples

struct MyStruct {
    int_field: u8,
    string_field: String,
}

// Assuming an OCaml record declaration like:
//
//      type my_struct = {
//          int_field: int;
//          string_field: string;
//      }
//
// NOTE: What is important is the order of the fields, not their names.

impl_to_ocaml_record! {
    // Optionally, if Rust and OCaml types don't match:
    // RustType => OCamlType { ... }
    MyStruct {
        // optionally `=> expr` can be used to preprocess the field value
        // before the conversion into OCaml takes place.
        // Inside the expression, a variable with the same name as the field
        // is bound to a reference to the field value.
        int_field: OCamlInt => { *int_field as i64 },
        string_field: String,
    }
}