OCaml C stubs

result.c

#include <caml/mlvalues.h>
#include <caml/memory.h>
#include <caml/alloc.h>

// Reference: http://decapode314.free.fr/ocaml/ocaml-wrapping-c.html
// Reference: https://ocaml.org/manual/intfc.html

// This stub return a (int,string) result

value esy_test_result(value unit) {
    CAMLparam1( unit );
    CAMLlocal1( result );

    // Ok 42
    result = caml_alloc(1, 0);
    Store_field( result, 0, Val_int(42) );
    
    // Error "the walking camel"
    // result = caml_alloc(1, 1);
    // char *s = "the walking camel";
    // Store_field( result, 0, caml_copy_string(s) );
    
    CAMLreturn(result);
}