Polymorphic Symmetric Multiple Dispatch with Variance Gyunghee Park, - - PowerPoint PPT Presentation

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Polymorphic Symmetric Multiple Dispatch with Variance Gyunghee Park, - - PowerPoint PPT Presentation

Apr 28, 2023 924 likes •1.11k views

Polymorphic Symmetric Multiple Dispatch with Variance Gyunghee Park, Jaemin Hong, Guy L. Steele Jr., Sukyoung Ryu POPL '19 Method Overloading add(x: Int, y: Int): Int = add(x: List, y: List): List = add(x: SortedList, y: List):

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Polymorphic Symmetric Multiple Dispatch with Variance

Gyunghee Park, Jaemin Hong, Guy L. Steele Jr., Sukyoung Ryu POPL '19

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Method Overloading

add(x: Int, y: Int): Int = … add(x: List, y: List): List = … add(x: SortedList, y: List): SortedList = … add(x: SortedList, y: SortedList): SortedList = …

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Method Dispatch

add(x: Int, y: Int): Int = … add(x: List, y: List): List = … add(x: SortedList, y: List): SortedList = … add(x: SortedList, y: SortedList): SortedList = … a: List = SortedList(1, 3, 5) b: List = SortedList(2, 4, 6) add(a, b)

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SortedList List

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Method Dispatch

add(x: Int, y: Int): Int = … add(x: List, y: List): List = … add(x: SortedList, y: List): SortedList = … add(x: SortedList, y: SortedList): SortedList = … a: List = SortedList(1, 3, 5) b: List = SortedList(2, 4, 6) add(a, b)

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SortedList List

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Static Dispatch

add(x: Int, y: Int): Int = … add(x: List, y: List): List = … add(x: SortedList, y: List): SortedList = … add(x: SortedList, y: SortedList): SortedList = … a: List = SortedList(1, 3, 5) b: List = SortedList(2, 4, 6) add(a, b)

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SortedList List

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Single Dispatch

add(x: Int, y: Int): Int = … add(x: List, y: List): List = … add(x: SortedList, y: List): SortedList = … add(x: SortedList, y: SortedList): SortedList = … a: List = SortedList(1, 3, 5) b: List = SortedList(2, 4, 6) add(a, b)

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SortedList List

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Single Dispatch

add(x: Int, y: Int): Int = … add(x: List, y: List): List = … add(x: SortedList, y: List): SortedList = … add(x: SortedList, y: SortedList): SortedList = … a: List = SortedList(1, 3, 5) b: List = SortedList(2, 4, 6) add(a, b)

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SortedList List

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Binary Method Problem

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Odersky et al., Programmin in Scala (3rd Ed.), Ch. 30 Object Equality

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Symmetric Multiple Dispatch

add(x: Int, y: Int): Int = … add(x: List, y: List): List = … add(x: SortedList, y: List): SortedList = … add(x: SortedList, y: SortedList): SortedList = … a: List = SortedList(1, 3, 5) b: List = SortedList(2, 4, 6) add(a, b)

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SortedList List

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add(x: Int, y: Int): Int = … add(x: List, y: List): List = … add(x: SortedList, y: List): SortedList = … add(x: SortedList, y: SortedList): SortedList = … a: List = SortedList(1, 3, 5) b: List = SortedList(2, 4, 6) add(a, b)

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SortedList List

Symmetric Multiple Dispatch

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Unambiguity

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add(x: List, y: SortedList): List = … add(x: SortedList, y: List): List = … a: List = SortedList(1, 3, 5) b: SortedList = SortedList(2, 4, 6) add(a, b) SortedList List

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Unambiguity

add(x: List, y: SortedList): List = … add(x: SortedList, y: List): List = … a: List = SortedList(1, 3, 5) b: SortedList = SortedList(2, 4, 6) add(a, b) SortedList List

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Type Preservation

add(x: List, y: SortedList): SortedList = … add(x: SortedList, y: SortedList): List = … a: List = SortedList(1, 3, 5) b: SortedList = SortedList(2, 4, 6) add(a, b) SortedList List

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Type Preservation

add(x: List, y: SortedList): SortedList = … add(x: SortedList, y: SortedList): List = … a: List = SortedList(1, 3, 5) b: SortedList = SortedList(2, 4, 6) add(a, b): SortedList SortedList List

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Overloading Rules

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Overloading Rules

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