A swift 4 KeyPath journey

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\Pen.pineapple.apple.pen A Swift 4 KeyPath Journey including el duderino, erased types, & a thinking cat Pikotaro - PPAP Elmar Kretzer - @elmkretzer

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KeyWhat? new Swift 4 feature w/ more than 10 yrs Obj-C xp [dude setValue:@"lebowski" forKey:@"lastname"]; The Big Lebowski © Copyright Gramercy Pictures

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the basics AnyKeyPath PartialKeyPath KeyPath WritableKeyPath

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like a getter A) straight forward B) wrapped in function C) by KeyPath

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like a setter A) straight forward B) wrapped in function C) by KeyPath

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chain’em

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any special tricks? https://www.instagram.com/corgnelius/ actually cool

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supports type inferrence Generic Typealias for some optional something from a list of somethings Actually, something is an Int

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supports optionals Chained optional properties - but only read

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supports appending 1. KeyPath from Dictionary to Dictionary.Keys 2. KeyPath from Dictionary.Keys to Int 3. Compose both

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A single expression that deﬁnes types and logic. so what?

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... so let’s assume two distinct types & we want to map from one to the other and back again. Read & Write with same Expression...

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LIVE CODING

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Thanks for listening Follow-Up article including gists on: http://elm4ward.github.io/ Twitter: @elmkretzer