I've been writing Rust full-time with a small team for over a year now. Throughout, I've lamented the lack of clear best practices around defining error types. One day, I'd love to write up my journey and enumerate the various strategies I've both seen and tried. Today is not that day.
Today, I want to reply to a blog post that almost perfectly summarised my current practice.
Go read it; I'll wait!
| // | |
| // ContentView.swift | |
| // SwiftUIPlayground | |
| // | |
| // Created by BJ Homer on 4/26/21. | |
| // | |
| import SwiftUI | |
The libdispatch is one of the most misused API due to the way it was presented to us when it was introduced and for many years after that, and due to the confusing documentation and API. This page is a compilation of important things to know if you're going to use this library. Many references are available at the end of this document pointing to comments from Apple's very own libdispatch maintainer (Pierre Habouzit).
My take-aways are:
You should create very few, long-lived, well-defined queues. These queues should be seen as execution contexts in your program (gui, background work, ...) that benefit from executing in parallel. An important thing to note is that if these queues are all active at once, you will get as many threads running. In most apps, you probably do not need to create more than 3 or 4 queues.
Go serial first, and as you find performance bottle necks, measure why, and if concurrency helps, apply with care, always validating under system pressure. Reuse
| // Algorithm W | |
| // From Principal Types for functional programs | |
| // http://web.cs.wpi.edu/~cs4536/c12/milner-damas_principal_types.pdf | |
| // by bkase | |
| // STD library | |
| infix operator <>: AdditionPrecedence | |
| extension Dictionary { | |
| static func <>(lhs: Dictionary, rhs: Dictionary) -> Dictionary { | |
| var d: [Key: Value] = [:] |
| // UICollectionView Objective-C example | |
| - (void)viewWillAppear:(BOOL)animated { | |
| [super viewWillAppear:animated]; | |
| NSIndexPath *selectedIndexPath = [[self.collectionView indexPathsForSelectedItems] firstObject]; | |
| if (selectedIndexPath != nil) { | |
| id<UIViewControllerTransitionCoordinator> coordinator = self.transitionCoordinator; | |
| if (coordinator != nil) { | |
| [coordinator animateAlongsideTransition:^(id<UIViewControllerTransitionCoordinatorContext> context) { |
| // | |
| // Created by はるふ on 2017/12/11. | |
| // Copyright © 2017年 ha1f. All rights reserved. | |
| // | |
| import Foundation | |
| import CoreImage | |
| import AVFoundation | |
| extension CIFilter { |
| // This example shows how higher-kinded types can be emulated in Swift today. | |
| // It acheives correct typing at the cost of some boilerplate, manual lifting and an existential representation. | |
| // The technique below was directly inspired by the paper Lightweight Higher-Kinded Polymorphism | |
| // by Jeremy Yallop and Leo White found at http://ocamllabs.io/higher/lightweight-higher-kinded-polymorphism.pdf | |
| /// `ConstructorTag` represents a type constructor. | |
| /// `Argument` represents an argument to the type constructor. | |
| struct Apply<ConstructorTag, Argument> { | |
| /// An existential containing a value of `Constructor<Argument>` | |
| /// Where `Constructor` is the type constructor represented by `ConstructorTag` |