cl-interpret: Tuple structs + fix tuple member access

compiler/cl-interpret/src/function.rs

@@ -21,12 +21,16 @@ pub struct Function {
     decl: Rc<FnDecl>,
     /// Stores data from the enclosing scopes
     upvars: RefCell<Upvars>,
+    is_constructor: bool,
 }
 
 impl Function {
     pub fn new(decl: &FnDecl) -> Self {
         // let upvars = collect_upvars(decl, env);
-        Self { decl: decl.clone().into(), upvars: Default::default() }
+        Self { decl: decl.clone().into(), upvars: Default::default(), is_constructor: false }
+    }
+    pub fn new_constructor(decl: FnDecl) -> Self {
+        Self { decl: decl.into(), upvars: Default::default(), is_constructor: true }
     }
     pub fn decl(&self) -> &FnDecl {
         &self.decl
@@ -54,6 +58,9 @@ impl Callable for Function {
         if args.len() != bind.len() {
             return Err(Error::ArgNumber { want: bind.len(), got: args.len() });
         }
+        if self.is_constructor {
+            return Ok(ConValue::TupleStruct(Box::new((*name, args.into()))));
+        }
         let Some(body) = body else {
             return Err(Error::NotDefined(*name));
         };