Right, though the embedding is trivial, the conceptual distinction is not. In Lean, a subtype is a refinement that restricts by proof. In OOP, a subclass augments or overrides behavior. It's composition versus inheritance. The trivial embedding masks a fundamental shift in what "subtype" means.
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Emphasis on "technically". The embedding is trivial. The Lean docs linked by the GP suggest to put those technicalities aside:
Right, though the embedding is trivial, the conceptual distinction is not. In Lean, a subtype is a refinement that restricts by proof. In OOP, a subclass augments or overrides behavior. It's composition versus inheritance. The trivial embedding masks a fundamental shift in what "subtype" means.