Rewrote lower type bounds section of tour #760
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SethTisue
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Apr 24, 2017
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| While [upper type bounds](upper-type-bounds.html) limit a type to a subtype of another type, *lower type bounds* declare a type to be a supertype of another type. The term `T >: A` expresses that the type parameter `T` or the abstract type `T` refer to a supertype of type `A`. | ||
| While [upper type bounds](upper-type-bounds.html) limit a type to a subtype of another type, *lower type bounds* declare a type to be a supertype of another type. The term `T >: A` expresses that the type parameter `T` or the abstract type `T` refer to a supertype of type `A`. In most cases, `A` will be the type parameter of the class and `T` will be the type parameter of a method. |
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I'd suggest using B instead of T, this matches the style used in the standard library
| ```tut | ||
| trait Mammal | ||
| case class AfricanSwallow() extends Mammal | ||
| case class EuropeanSwallow() extends Mammal |
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Yes, but then I'm not sure how to make it work with the example below.
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You'd have to do e.g. ListNode[AfricanSwallow.type]. Yeah, OK, better as is, actually
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| case class Nil[+T]() extends Node[T] { |
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will case object Nil extends Node[Nothing] work?
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Doesn't seem to
| ListNode(elem, this) | ||
| ```tut:fail | ||
| trait Node[+T] { | ||
| def prepend(elem: T) |
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