Macro ocaml_interop::ocaml_export

macro_rules! ocaml_export {
    {} => { ... };
    {
        fn $name:ident$(|$byte_name:ident)?( $cr:ident, $($args:tt)*) -> f64
           $body:block

        $($t:tt)*
    } => { ... };
    {
        fn $name:ident$(|$byte_name:ident)?( $cr:ident, $($args:tt)*) $(-> $rtyp:ty)?
           $body:block

        $($t:tt)*
    } => { ... };
    {
        fn $name:ident$(|$byte_name:ident)?( $($invalid_args:tt)* ) $(-> $rtyp:ty)?
           $body:block

        $($t:tt)*
    } => { ... };
}

Defines Rust functions callable from OCaml.

The first argument in these functions declarations is a name to bind a &mut OCamlRuntime.

Arguments and return values must be of type OCamlRef<T>, or f64 in the case of unboxed floats.

The return type defaults to OCaml<()> when omitted.

To generate a bytecode-callable version of the function (needed when the function has 6 or more arguments), add a second name to the function separated by | (see last example).

Examples

ocaml_export! {
    fn rust_twice(cr, num: OCamlRef<OCamlInt>) -> OCaml<OCamlInt> {
        let num: i64 = num.to_rust(cr);
        unsafe { OCaml::of_i64_unchecked(num * 2) }
    }

    fn rust_twice_boxed_i32(cr, num: OCamlRef<OCamlInt32>) -> OCaml<OCamlInt32> {
        let num: i32 = num.to_rust(cr);
        let result = num * 2;
        result.to_ocaml(cr)
    }

    fn rust_add_unboxed_floats_noalloc(_cr, num: f64, num2: f64) -> f64 {
        num * num2
    }

    fn rust_twice_boxed_float(cr, num: OCamlRef<OCamlFloat>) -> OCaml<OCamlFloat> {
        let num: f64 = num.to_rust(cr);
        let result = num * 2.0;
        result.to_ocaml(cr)
    }

    fn rust_increment_ints_list(cr, ints: OCamlRef<OCamlList<OCamlInt>>) -> OCaml<OCamlList<OCamlInt>> {
        let mut vec: Vec<i64> = ints.to_rust(cr);

        for i in 0..vec.len() {
            vec[i] += 1;
        }

        vec.to_ocaml(cr)
    }

    fn rust_make_tuple(cr, fst: OCamlRef<String>, snd: OCamlRef<OCamlInt>) -> OCaml<(String, OCamlInt)> {
        let fst: String = fst.to_rust(cr);
        let snd: i64 = snd.to_rust(cr);
        let tuple = (fst, snd);
        tuple.to_ocaml(cr)
    }

   fn rust_rust_add_7ints|rust_rust_add_7ints_byte(
       cr,
       int1: OCamlRef<OCamlInt>,
       int2: OCamlRef<OCamlInt>,
       int3: OCamlRef<OCamlInt>,
       int4: OCamlRef<OCamlInt>,
       int5: OCamlRef<OCamlInt>,
       int6: OCamlRef<OCamlInt>,
       int7: OCamlRef<OCamlInt>,
   ) -> OCaml<OCamlInt> {
       let int1: i64 = int1.to_rust(cr);
       let int2: i64 = int2.to_rust(cr);
       let int3: i64 = int3.to_rust(cr);
       let int4: i64 = int4.to_rust(cr);
       let int5: i64 = int5.to_rust(cr);
       let int6: i64 = int6.to_rust(cr);
       let int7: i64 = int7.to_rust(cr);
       unsafe { OCaml::of_i64_unchecked(int1 + int2 + int3 + int4 + int5 + int6 + int7) }
   }
}