Hipster oriented programming (Mobilization Lodz 2015)

Jens Ravens
Developer at nerdgeschoss
iOS/ OS X (Swift)
Server / Backend (Ruby)
@JensRavens
jensravens.de
nerdgeschoss.de

I hate monads already. Even if it’s
the most useful, elegant thing - it’s
all what’s wrong about hype based
hipster-programming in one word.
- tweet after UIKonf

Is it really functional
programming if you don't give a
talk about it?
- @alejandrocrosa

This talk is not about
functional programming.

a person who follows the latest
trends and fashions, especially those
regarded as being outside the
cultural mainstream.
- Wikipedia

Imperative
Do this 5 times!
func nullToNil(dict: [String: AnyObject])->[String: AnyObject]{
var cleaned = [String: AnyObject]()
for (key, value) in dict {
if !(value is NSNull) {
cleaned[key] = value
}
}
return cleaned
}

Functional
Same input, same output.
let l = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
let sum = l.reduce(+) // 55

Object Oriented
Put your family of objects in a
room and let them talk.

Protocol Oriented
You have a lot of equatable,
comparable, parseable, archiveable,
transmittable, displayable objects.

Spaghetti Oriented
JSON parsing.

What is state anyway?
class ViewController: UIViewController, UITableViewDelegate {
var selectedItem: Item?
func updateView() {
// do something to update the display
}
func tableView(tableView: UITableView,
didSelectRowAtIndexPath indexPath: NSIndexPath) {
selectedItem = findItemAtIndex(indexPath)
}
}

Question State How to recognise?
IP
imperative
How? a lot of nested loops and assignments
OOP
object oriented
How?
(but encapsulated)
encapsulated
state
seperation of concerns
“unix principle”
POP
protocol oriented
What? encapsulated
objects implementing hundreds
of protocols.
FP
functional
What? no state.
you have no idea what it’s doing,
but it’s short and beautiful.
FRP
functional reactive
When?
over my dead
lambda.
you’re constantly ﬂatMapping

They all mix pretty well.
- pretty big secret

Monads.
http://fuckingmonads.com

Signals.
jensravens.de/series/functional-reactive-programming-in-swift/

Mapping Arrays and
Collections.

idea 1
treating your user as an
interface

user interface
Recipe
Recipe
Recipe
Recipe
Recipe
protocol User {
func selectRecipe(recipies: [Recipe], completion:Recipe->Void)
}

user interface
Recipe
Recipe
Recipe
Recipe
Recipe
protocol User {
func selectRecipe(recipies: [Recipe], completion:Recipe?->Void)
}

user interface
Recipe
Recipe
Recipe
Recipe
Recipe
protocol User {
func selectSingle(collection: [Selectable], completion:Selectable?->Void)
}

user interface
Recipe
Recipe
Recipe
Recipe
Recipe
func downloadStuff(term: String, completion: Result<[Recipe]>->Void){
// networking and error handling
}
class UserSelection: UIViewController, User {
static func selectRecipe(presentingViewController: UIViewController)
(recipies: [Recipe], completion: Result<Recipe> -> Void) {
// present your view controller here and save the completion block
}
}
let searchVC = // your current vc
let textField = // the textfield used for typing
textField
.textSignal
.flatMap(downloadStuff)
.flatMap(UserSelection.selectRecipe(searchVC))
.next { recipe in
// do whatever you like
}
.error { error in
// something went wrong on the way
}

abstract servers
public typealias Headers = [String: String]
public typealias Environment = [String: AnyObject]
public typealias StatusCode = Int
public typealias Response = (StatusCode, Headers, ContentStreamable)
public typealias Swagable = Request throws -> Response
let HelloWorld: Swagable = { env in
return (200, [:], "Hello World")
}

idea 3
common behavior in
protocols

protocol Contextable {
func showContext(gestureRecognizer: UIGestureRecognizer)
func viewControllerForContext(context: Item) -> UIViewController?
func contextViewControllerForContext(context: Item) ->
UIViewController?
func contextForGestureRecognizer(gestureRecognizer:
UIGestureRecognizer) -> Item?
// the only required method
func contextForIndexPath(indexPath: NSIndexPath) -> Item?
}

extension Contextable {
func viewControllerForContext(context: Item) -> UIViewController?
{
return self as? UIViewController
}
func contextForGestureRecognizer(gestureRecognizer:
UIGestureRecognizer) -> Item? {
// find the clicked indexpath
}
}

extension ChannelViewController: Contextable {
@IBAction func triggerContext(gestureRecognizer:
UIGestureRecognizer) {
showContext(gestureRecognizer)
}
func contextForIndexPath(indexPath: NSIndexPath) -> Item? {
return dataSource.itemForIndexPath(indexPath)
}
}

These are just concepts.
They won’t hurt you, they
won’t take away your job.

It’s more out there than just
object oriented
programming.

object oriented programming
has a lot of hidden gems you
might not be aware of yet.

learning from
other plattforms

these are amazing times
to be a developer

do not just read about
your plattform

Hipster oriented programming (Mobilization Lodz 2015)

Functors, Applicatives
and Monads in Pictures.
http://adit.io/posts/2013-04-17-
functors,_applicatives,_and_monads_in_pictures.html

The Introduction to RP
you’ve been missing.
https://gist.github.com/staltz/868e7e9bc2a7b8c1f754

Imperative Programming In Swift (Graham Lee)
sicpers.info/2015/07/imperative-programming-in-swift/
Protocol-Oriented Programming in Objective-C
sicpers.info/2015/06/protocol-oriented-programming-in-
objective-c/
Mutable objects in immutable objects in object-oriented
programming in functional programming in Swift
sicpers.info/2015/06/mutable-objects-in-immutable-
objects-in-object-oriented-programming-in-functional-
programming-in-swift/

keep searching for
new frontiers

use the right tool
for the right job

Thank you.
@JensRavens
jensravens.de

Hipster oriented programming (Mobilization Lodz 2015)

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