Add prelude and while macro

This commit introduces a new prelude file that defines the `while` macro
and registers it during environment bootstrapping. The `again` macro has
been updated to accept multiple arguments for its recursive call, and
several examples have been adjusted to reflect this change.
Additionally, the `MacroRegistry` in the compiler is now cloneable and
can be moved out of the `MacroExpander`.

src/ast/environment.rs

@@ -32,6 +32,7 @@ pub struct Environment {
     pub monomorph_cache: Rc<RefCell<MonoCache>>,
     pub debug_mode: bool,
     pub optimization: bool,
+    pub macro_registry: Rc<RefCell<MacroRegistry>>,
 }
 
 struct EnvFunctionRegistry {
@@ -104,6 +105,7 @@ impl Environment {
             monomorph_cache: Rc::new(RefCell::new(HashMap::new())),
             debug_mode: false,
             optimization: true,
+            macro_registry: Rc::new(RefCell::new(MacroRegistry::new())),
         };
         env.register_stdlib();
         env
@@ -119,7 +121,15 @@ impl Environment {
             global_types: self.global_types.clone(),
             global_values: self.global_values.clone(),
         };
-        MacroExpander::new(MacroRegistry::new(), evaluator)
+        MacroExpander::new(self.macro_registry.borrow().clone(), evaluator)
+    }
+
+    fn eval_prelude(&self, source: &str) {
+        let mut parser = crate::ast::parser::Parser::new(source).expect("Failed to parse prelude");
+        let untyped_ast = parser.parse_expression().expect("Failed to parse prelude expression");
+        let mut expander = self.get_expander();
+        let _ = expander.expand(untyped_ast).expect("Failed to expand prelude");
+        *self.macro_registry.borrow_mut() = expander.into_registry();
     }
 
     pub fn register_native(
@@ -174,6 +184,7 @@ impl Environment {
 
     fn register_stdlib(&self) {
         rtl::register(self);
+        self.eval_prelude(include_str!("rtl/prelude.myc"));
     }
 
     pub fn dump_ast(&self, source: &str) -> Result<String, String> {