Better Code for a Better World

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(Welcome!)

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Josh Abernathy @joshaber

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for a ReactiveCocoa Better World

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for a Better World Better Code

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Some rantings about code and an introduction to using ReactiveCocoa to solve all of the problems currently facing mankind—a phrase I only use somewhat facetiously because if software really is taking over the world then better software can, in a very real way , lead to a better world, assuming you’re not writing software for a doomsday device, in which case you should go ahead and write terrible software—but mostly focusing on writing reactive user interfaces because that’s nice and demoable.

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PERSPECTIVE

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Bug-free (ish)

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Bug-free (ish) Expressive

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Bug-free (ish) Concise Expressive

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PHILOSOPHY

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“Out of the Tarpit”

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Complexity is STATE

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2 states

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2 states 4 states

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2 states 4 states 8 states

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2 states 4 states 8 states 16 states

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32 states ... 64 states ... 128 states ... gazillion states ...

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Minimize state

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Minimize state by deriving it

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2 states

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2 states 4 states

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2 states 4 states 4 states

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Complexity is CONTROL

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Say what Not how

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What and how

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What

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What and how

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What

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Complexity is the ENEMY

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Is this complexity inherent to the problem?

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i.e.,

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Would a normal person think this is necessary?

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ReactiveCocoa To The Rescue!

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Declarative!

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Minimal state! (we’ll see that more later)

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PRAGMATISM

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What is it?

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It’s like a series of tubes...

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A sequence of values over time.

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A stream of things.

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int a = 0; a = 1; ... a = 2;

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0 value of a: 1 2

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(We already do this with variables, we just pretend we don’t.)

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a RACSubscribable b c

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a RACSubscribable

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RACSubscribable

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a b c RACSubscriber

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???

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UI events

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(20, 20)

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(20, 20) (100, 0)

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(20, 20) (100, 0) (120, 50)

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h h

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h hi h hi

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h hi hi! h hi hi!

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KVO

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Async work

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Network request

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KVO property = UI events = Network request = Async work = ??? = Subscribables

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So what?

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Shared Vocabulary

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Shared Toolset

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+combineLatest:reduce: -select: -where: -distinctUntilChanged -throttle: ...and infinity more...

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Composable

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To the Xcode!

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Bug-free (ish)

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Bug-free (ish) Expressive

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Bug-free (ish) Concise Expressive

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Minimize state by deriving it

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Say what Not how

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github.com/github/ReactiveCocoa More Info: Reactive Extensions (Rx) @joshaber elm-lang.org Functional Reactive Programming

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(Thanks!)