Improve arg parsing

crates/pile-config/src/objectpath/mod.rs

@@ -41,8 +41,11 @@ pub enum PathSegment {
 	/// Go to root node (`$` identifier)
 	Root,
 
-	/// Go to a child of the current object
-	Field(Label),
+	/// Go to a child of the current object.
+	Field {
+		name: Label,
+		args: Option<SmartString<LazyCompact>>,
+	},
 
 	/// Go to an element of the current list
 	Index(i64),