andymatuschak

A composable pattern for pure state machines with effects

State machines are everywhere in interactive systems, but they're rarely defined clearly and explicitly. Given some big blob of code including implicit state machines, which transitions are possible and under what conditions? What effects take place on what transitions?

There are existing design patterns for state machines, but all the patterns I've seen complect side effects with the structure of the state machine itself. Instances of these patterns are difficult to test without mocking, and they end up with more dependencies. Worse, the classic patterns compose poorly: hierarchical state machines are typically not straightforward extensions. The functional programming world has solutions, but they don't transpose neatly enough to be broadly usable in mainstream languages.

Here I present a composable pattern for pure state machiness with effects,

roop

/* A responder chain implementation for a hypothetical pure-Swift
 * equivalent for UIKit.
 * More info at: http://roopc.net/posts/2016/swifty-responder-chain/
 */

/* A responder is something that has an optional next responder,
   so that we can have a chain of responders. */

protocol Responder {
    var nextResponder: Responder? { get }

blessingLopes

public protocol Selfie: CustomStringConvertible {}

extension Selfie {

  var description: String {
    let mirror = Mirror(reflecting: self)
    return "\(mirror.subjectType)( \(mirror.children.map({ "\($0!): \($1) "}).joinWithSeparator(", ")))"
   }
}

pcperini

import UIKit

public protocol ConstraintStateMachineType: class {
    // MARK: Types
    typealias State: RawRepresentable
    
    // MARK: Properties
    var state: State? { get set }
    var allConstraints: [NSLayoutConstraint] { get }
    

jamtur01

These are the Kickstarter Engineering and Data role definitions for both teams.

Technical	Data	People
Junior Software Engineer
Software Engineer	Data Analyst
Senior Software Engineer	Data Scientist	Engineering Manager
Staff Engineer	VP of Data	Engineering Director
Principal Engineer		CTO

plumhead

extension String {
    func size(withAttributes attrs: [String:AnyObject], constrainedTo box: NSSize) -> NSRect {
        let storage = NSTextStorage(string: self)
        let container = NSTextContainer(containerSize: NSSize(width: box.width, height: box.height))
        let layout = NSLayoutManager()
        layout.addTextContainer(container)
        storage.addLayoutManager(layout)
        storage.addAttributes(attrs, range: NSMakeRange(0, storage.length))
        container.lineFragmentPadding = 0.0
        let _ = layout.glyphRangeForTextContainer(container)

Abizern

//
//  LoggingPrint.swift
//

import Foundation

/**
 Prints the filename, function name, line number and textual representation of `object` and a newline character into
 the standard output if the build setting for "Active Complilation Conditions" (SWIFT_ACTIVE_COMPILATION_CONDITIONS) defines `DEBUG`.

dorentus

#!/usr/bin/env xcrun swift
import Foundation
import CoreText

func input_from_stdin() -> String {
    var input = ""
    let stdin = FileHandle.standardInput
    let zeroData = Data()
    while true {
        let input_data = stdin.availableData

staltz

The introduction to Reactive Programming you've been missing

(by @andrestaltz)

---

This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

---

bmatcuk

How to Symbolize OSX Crash Logs

Unfortunately, xcode does not yet have support for importing OSX crash logs and symbolizing them. Therefore, you must use the command line and a little bit of manual work.

1. Find your dSYM file.
   1. Assuming you are using xcode's archive functionality, open the Organizer window from the Window menu.
   2. Click the Archives tab.
   3. Right click on the appropriate build and select Show in Finder.
   4. When Finder opens, right click on the selected archive and select Show Package Contents.
   5. Navigate to the dSYM directory and copy the appropriate dSYM file to a temporary directory.
2. Then navigate to Products, then Applications, and copy the app file to the same temporary directory.