Added Rust support to the Fun core. (0.38.0)

examples/rust_hello.fun

@@ -0,0 +1,32 @@
+#!/usr/bin/env fun
+
+/*
+ * This file is part of the Fun programming language.
+ * https://fun-lang.xyz/
+ *
+ * Copyright 2025 Johannes Findeisen <you@hanez.org>
+ * Licensed under the terms of the Apache-2.0 license.
+ * https://opensource.org/license/apache-2-0
+ *
+ * Added: 2026-01-27
+ */
+
+/*
+ * Rust-backed opcode demo: rust_hello()
+ *
+ * Build instructions:
+ *   - Default builds disable Rust integration.
+ *   - Enable it via: cmake -S . -B build_debug -DFUN_WITH_RUST=ON
+ *   - Then: cmake --build build_debug --target fun
+ *
+ * Run:
+ *   build_debug/fun examples/rust_hello.fun
+ *
+ * Expected output (with FUN_WITH_RUST=ON):
+ *   Hello from Rust ops!
+ *
+ * If built without Rust, calling rust_hello() will raise a runtime error
+ * explaining that Rust integration is disabled.
+ */
+
+print(rust_hello())