Athosone

A gentle introduction to Clojure

Ian Truslove

Den of Clojure

2016-04-21

---

Athosone

// Consider this function:
func fetchPost(by postId: Int, completion: @escaping (Post?, Error?) -> Void) {
  ...
}
// Using our extension to use an observable
// fetchPostObservable looks like: fetchPostObservable(postId) -> Observable<Post>
let fetchPostObservable = Observable.fromAsync(postService.getPost(postId:completion:))

// Now to fetch a post you just have to call it just like you would call any function which returns an Observable:
fecthPostObservable(10).subscribe(onNext: { (post) in

Athosone

enum LogLevel: String {
    case debug
    case error
}

func logMessage(level: LogLevel, message: String) {
    print("[\(level)] \(message)")
}

// Without Currying

Athosone

extension Observable {
    
    // MARK: For completionBlock(Element, Error) template methods
    
    public static func fromAsync(_ asyncRequest: @escaping (@escaping (Element?, Error?) -> Void) -> Void) -> Observable<Element> {
        return Observable.create { (o) -> Disposable in
            asyncRequest { res, error in
                if let err = error {
                    o.onError(err)
                    return

Athosone

// We apply curry to the log message func
let logCurried = curry(logMessage)
// logCurried can be represented like this: logCurried -> (LogLevel) -> (String) -> Void

let debug = logCurried(.debug)
// debug can be represented like this: debug -> (String) -> Void
debug("Log debug")

Athosone

enum LogLevel: String {
    case debug
    case error
}

func logMessage(level: LogLevel, message: String) {
    print("[\(level)] \(message)")
}

Athosone

func curry<A, B, C>(_ fn: @escaping (A, B) -> C) -> (A) -> (B) -> C {
    return { (a: A) in
        return { (b: B) in
            return fn(a, b)
        }
    }
}

Athosone

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        guard let dummyCell: OABSubCategoryMenuCell = Bundle.main.loadNibNamed("OABSubCategoryMenuCell", owner: self, options: nil)?.first as? OABSubCategoryMenuCell else {
            return CGSize.zero
        }
        dummyCell.setContent(subCat: self.subCategories[indexPath.row], isSelected: false)
        dummyCell.setNeedsLayout()
        dummyCell.layoutIfNeeded()
        let size: CGSize = dummyCell.contentView.systemLayoutSizeFitting(UILayoutFittingCompressedSize)
        return size
    }

Athosone

: public enum BundleData
 {
  ItemPosition,
  UserName
 }

 public static class Extensions
 {
  public static int GetBundleData(this Intent intent, BundleData data, int defaultValue)
   => intent.Extras.GetInt(data.ToString(), defaultValue);

Athosone

//
//  THTriangleView.swift
//  thirsty
//
//  Created by Werck Ayrton on 23/06/2015.
//  Copyright (c) 2015 Nyu Web Developpement. All rights reserved.
//

import UIKit