conlang: Add constructor expression for structs!

grammar:
- Add new rules `PathLike`, `Structor`, `Fielder`
- Replace Path with PathLike in Primary expressions

cl-ast:
- Add nodes for Structor and Fielder

cl-parser:
- Add branch to path-expression parsing
- Parse Structor bodies

interpret:
- Add TODO

compiler/cl-interpret/src/interpret.rs

@@ -126,17 +126,18 @@ impl Interpret for Expr {
 impl Interpret for ExprKind {
     fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
         match self {
+            ExprKind::Empty => Ok(ConValue::Empty),
             ExprKind::Assign(v) => v.interpret(env),
             ExprKind::Binary(v) => v.interpret(env),
             ExprKind::Unary(v) => v.interpret(env),
             ExprKind::Index(v) => v.interpret(env),
+            ExprKind::Structor(v) => v.interpret(env),
             ExprKind::Path(v) => v.interpret(env),
             ExprKind::Literal(v) => v.interpret(env),
             ExprKind::Array(v) => v.interpret(env),
             ExprKind::ArrayRep(v) => v.interpret(env),
             ExprKind::AddrOf(v) => v.interpret(env),
             ExprKind::Block(v) => v.interpret(env),
-            ExprKind::Empty => Ok(ConValue::Empty),
             ExprKind::Group(v) => v.interpret(env),
             ExprKind::Tuple(v) => v.interpret(env),
             ExprKind::Loop(v) => v.interpret(env),
@@ -322,6 +323,11 @@ impl Interpret for Index {
         Ok(head)
     }
 }
+impl Interpret for Structor {
+    fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
+        todo!("struct construction in {env}")
+    }
+}
 impl Interpret for Path {
     fn interpret(&self, env: &mut Environment) -> IResult<ConValue> {
         let Self { absolute: _, parts } = self;