Parse type aliases

crates/frontend/src/ast.rs

@@ -138,7 +138,9 @@ pub struct Relation<'db> {
 /// Parses [TypeAlias] from an [AstNode].
 #[salsa::tracked]
 pub fn type_alias<'db>(db: &'db dyn Database, ast: AstNode) -> TypeAlias<'db> {
-    todo!()
+    let name = ast.expect_field(db, "name").with_contents(db);
+    let ty = ty(db, ast.expect_field(db, "type"));
+    TypeAlias::new(db, name, ty)
 }
 
 /// An abstract type alias (syntax representation).