Value

The expression computing this Projection's value from the bound instance. Any `tx.Expression`; the bound instance is available as the `input` environment binding. A bare property is a `tx.PropertyRead` (`readSource` a `tx.VarRef` of `input`, `readProp` the property); a multi-step path is a `tx.Traverse`; an aggregate wraps the value in a `tx.ListAggregate` subclass; a derived label is a `tx.DisplayLabel`. Every property and path step resolves through the object model and is validated against the View's bound class at `kanonak validate` time.