Module rpc::server_fn

Server functions.

The "write it once, call it from anywhere" pattern (Dioxus/Leptos/Next.js server actions) — a thin JSON-marshaling layer over std::rpc (see rpc.h). SafeC has no macros/codegen to make a single function definition automatically usable on both sides the way those frameworks' #[server]/"use server" attributes do — you still define the server-side implementation and register it, and a client calls it by name — but the wire format (JSON in, JSON out, via std::Value — see std/serial/value.h, the same tree json.h/csv.h/yaml.h use) is handled for you, so a "server function" is just:

struct Value add_fn(const struct Value* args) {
    long long a = args->object_get("a")->as_int();
    long long b = args->object_get("b")->as_int();
    return Value::from_int(a + b);
}
server_fn_register("add", add_fn);
server_fn_serve(8080);   // on the server

int ok;
struct Value args = Value::object();
args.object_set("a", Value::from_int(2));
args.object_set("b", Value::from_int(3));
struct Value result = server_fn_call("localhost", 8080, "add", &args, &ok);
// result.as_int() == 5

All registered functions are served over one RPC path ("/fn/call"); the target function name travels inside the JSON payload ({"fn": "...", "args": ...}), not the URL, since std::rpc dispatches by exact path and a plain C function pointer (RpcMethodHandler) has no closure/userdata slot to carry a per-registration name through.