on Tue Jun 07 2016, Matthew Johnson <swift-evolution@swift.org> wrote:
>> , but haven't realized >> that if you step around the type relationships encoded in Self >> requirements and associated types you end up with types that appear to >> interoperate but in fact trap at runtime unless used in exactly the >> right way. > > Trap at runtime? How so? Generalized existentials should still be > type-safe. There are two choices when you erase static type relationships: 1. Acheive type-safety by trapping at runtime FloatingPoint(3.0 as Float) + FloatingPoint(3.0 as Double) // trap 2. Don't expose protocol requirements that involve these relationships, which would prevent the code above from compiling and prevent FloatingPoint from conforming to itself. > Or are you talking about the hypothetical types / behaviors people > think they want when they don’t fully understand what is happening... I don't know what you mean here. I think generalized existentials will be nice to have, but I think most people will want them to do something they can't possibly do. -- -Dave _______________________________________________ swift-evolution mailing list swift-evolution@swift.org https://lists.swift.org/mailman/listinfo/swift-evolution
