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nicklockwood / AnyFoo.swift
Last active Sep 26, 2019
POC for serializing heterogeneous array of structs using Codable in Swift
View AnyFoo.swift
import Foundation
enum FooType: String, Codable {
case bar, baz
protocol Foo: Codable {
var type: FooType { get }
nicklockwood / AnyFoo.swift
Last active Sep 18, 2019
POC for serializing heterogeneous array of classes using Codable in Swift
View AnyFoo.swift
import Foundation
enum FooType: String, Codable {
case bar, baz
protocol Foo: AnyObject, Codable {
var type: FooType { get }
View Withable.swift
/// Withable is a simple protocol to make constructing
/// and modifying objects with multiple properties
/// more pleasant (functional, chainable, point-free)
public protocol Withable {
public extension Withable {
/// Construct a new instance, setting an arbitrary subset of properties
init(with config: (inout Self) -> Void) {
View gist:35bc1734f2f8c97177010b1188345921
func tableView(_ tableView: NSTableView, objectValueFor tableColumn: NSTableColumn?, row: Int) ->
guard let obj = (self.representedObject as? ModelType)?.collection(at:row) else {
return nil
switch tableColumn?.identifier.rawValue ?? "" {
case "column1":
return obj.field1
case "column2":
return objc.field2
nicklockwood / StringsTest.swift
Last active Jan 16, 2019
string concat benchmarks
View StringsTest.swift
import XCTest
let count = 50000
class StringsTestTests: XCTestCase {
// MARK: Copying
func testInterpolation() {
var foo = ""
nicklockwood / main.swift
Created Dec 1, 2017
Thread-safe cache implementation benchmark
View main.swift
var cache = [Int: Int]()
let queue = DispatchQueue(label: "cacheQueue", attributes: .concurrent)
let iterations = 100000
// In the first run, cache is empty so we're writing each time
do {
let start = CFAbsoluteTimeGetCurrent()
for i in 0 ... iterations {
var exists = false
queue.sync {
nicklockwood / UnicodeScalarView.swift
Last active Sep 21, 2017
View UnicodeScalarView.swift
// This is a really simple drop-in replacement for String.UnicodeScalarView
// As of Swift 3.2, String.UnicodeScalarView no longer supports slice operations, and
// String.UnicodeScalarView.Subsequence is ~5x slower
// Only a small subset of methods are implemented, specifically the ones useful for
// implementing a parser or lexer that consumes a string by repeatedly calling popFirst()
// I've benchmarked popFirst() as ~7x faster than String.UnicodeScalarView.Subsequence in Swift 3.2 and 4.0
// The performance is close to that of String.UnicodeScalarView in Swift 3.1, but may be slightly worse in some use cases
View Pattern for Swift Errors.swift
// Swift's untyped errors are a goddam PiTA. Here's the pattern I use to try to work around this.
// The goal is basically to try to guarantee that every throwing function in the app throws an
// ApplicationError instead of some unknown error type. We can't actually enforce this statically
// But by following this convention we can simplify error handling
enum ApplicationError: Error, CustomStringConvertible {
// These are application-specific errors that may need special treatment
case specificError1
case specificError2(SomeType)
nicklockwood / error-propagation.swift
Last active Aug 17, 2017
Typed error use-case example
View error-propagation.swift
enum ValueError: Error {
case notFound
case typeMismatch
struct PropertyError: Error {
let name: String
let error: ValueError

A very basic JSON parser, written in [new language]. Only supports String, Int and Array so far.

json := "[42, \"hello\", [\"good\", \"bye\"]]"

JSON = String|Int|[JSON] // TODO: true, false, null, object

skipSpace(json: String) String {
    input := json
    while input.first == " " {
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