Add 31

.gitmodules

@@ -17,5 +17,5 @@
   path = 0025-zip-pt3/Vendor/swift-nonempty
   url = https://github.com/pointfreeco/swift-nonempty.git
 [submodule "0031-arbitrary/Vendor/Tagged"]
-	path = 0031-arbitrary/Vendor/Tagged
+	path = 0031-arbitrary-pt1/Vendor/Tagged
 	url = https://github.com/pointfreeco/swift-tagged.git

0031-arbitrary/Arbitrary.playground/Contents.swift → 0031-arbitrary-pt1/Arbitrary.playground/Pages/01-episode.xcplaygroundpage/Contents.swift

@@ -171,165 +171,13 @@ try Date(from: ArbitraryDecoder())
 try Date(from: ArbitraryDecoder())
 //try UUID(from: ArbitraryDecoder())
 
-import Tagged
-
 struct User: Decodable {
-  typealias Id = Tagged<User, UUID>
-
-  let id: Id
+  let id: Int
   let name: String
   let email: String
 }
 
-//print(try User(from: ArbitraryDecoder()))
-//print(try User(from: ArbitraryDecoder()))
-//print(try User(from: ArbitraryDecoder()))
-//print(try User(from: ArbitraryDecoder()))
-
-
-struct Gen<A> {
-  let run: () -> A
-}
-
-import Darwin
-let random = Gen(run: arc4random)
-
-extension Gen {
-  func map<B>(_ f: @escaping (A) -> B) -> Gen<B> {
-    return Gen<B> { f(self.run()) }
-  }
-}
-
-let uint64 = Gen<UInt64> {
-  let lower = UInt64(random.run())
-  let upper = UInt64(random.run()) << 32
-  return lower + upper
-}
-
-func int(in range: ClosedRange<Int>) -> Gen<Int> {
-  return Gen<Int> {
-    var delta = UInt64(truncatingIfNeeded: range.upperBound &- range.lowerBound)
-    if delta == UInt64.max {
-      return Int(truncatingIfNeeded: uint64.run())
-    }
-    delta += 1
-    let tmp = UInt64.max % delta + 1
-    let upperBound = tmp == delta ? 0 : tmp
-    var random: UInt64 = 0
-    repeat {
-      random = uint64.run()
-    } while random < upperBound
-    return Int(
-      truncatingIfNeeded: UInt64(truncatingIfNeeded: range.lowerBound)
-        &+ random % delta
-    )
-  }
-}
-
-func element<A>(of xs: [A]) -> Gen<A?> {
-  return int(in: 0...(xs.count - 1)).map { idx in
-    guard !xs.isEmpty else { return nil }
-    return xs[idx]
-  }
-}
-
-extension Gen {
-  func array(count: Gen<Int>) -> Gen<[A]> {
-    return Gen<[A]> {
-      Array(repeating: (), count: count.run())
-        .map { self.run() }
-    }
-  }
-}
-
-func uint8(in range: ClosedRange<UInt8>) -> Gen<UInt8> {
-  return int(in: Int(UInt8.min)...Int(UInt8.max))
-    .map(UInt8.init)
-}
-
-let string = uint8(in: .min ... .max)
-//  .map { String(UnicodeScalar($0)) }
-//  .map(UnicodeScalar.init)
-//  .map(String.init)
-  .map(UnicodeScalar.init >>> String.init)
-  .array(count: int(in: 0...280))
-  .map { $0.joined() }
-
-string.run()
-string.run()
-string.run()
-
-"DEADBEEF-DEAD-BEEF-DEAD-BEEFDEADBEEF"
-
-
-extension Gen where A == Character {
-  func string(count: Gen<Int>) -> Gen<String> {
-    return self.map(String.init).array(count: count).map { $0.joined() }
-  }
-}
-
-let hex = element(of: Array("0123456789ABCDEF")).map { $0! }
-let uuidString = Gen {
-  hex.string(count: .init { 8 }).run()
-    + "-" + hex.string(count: .init { 4 }).run()
-    + "-" + hex.string(count: .init { 4 }).run()
-    + "-" + hex.string(count: .init { 4 }).run()
-    + "-" + hex.string(count: .init { 12 }).run()
-}
-let randomUuid = uuidString.map(UUID.init).map { $0! }
-
-User(
-  id: randomUuid.map(User.Id.init).run(),
-  name: string.run(),
-  email: string.run()
-)
-
-
-let alpha = element(of: Array("abcdefghijklmnopqrstuvwxyz")).map { $0! }
-let namePart = alpha.string(count: int(in: 4...8))
-let capitalNamePart = namePart.map { $0.capitalized }
-let randomName = Gen<String> { capitalNamePart.run() + " " + capitalNamePart.run() }
-let randomEmail = namePart.map { $0 + "@pointfree.co" }
-let randomId = int(in: 1...1_000)
-
-
-func zip2<A, B>(_ a: Gen<A>, _ b: Gen<B>) -> Gen<(A, B)> {
-  return Gen<(A, B)> {
-    (a.run(), b.run())
-  }
-}
-
-zip2(randomId, randomName).run()
-zip2(randomId, randomName).run()
-zip2(randomId, randomName).run()
-
-func zip2<A, B, C>(with f: @escaping (A, B) -> C) -> (Gen<A>, Gen<B>) -> Gen<C> {
-  return { zip2($0, $1).map(f)}
-}
-
-func zip3<A, B, C>(_ a: Gen<A>, _ b: Gen<B>, _ c: Gen<C>) -> Gen<(A, B, C)> {
-  return zip2(a, zip2(b, c)).map { ($0, $1.0, $1.1) }
-}
-
-func zip3<A, B, C, D>(with f: @escaping (A, B, C) -> D) -> (Gen<A>, Gen<B>, Gen<C>) -> Gen<D> {
-  return { zip3($0, $1, $2).map(f) }
-}
-
-let randomUser = zip3(with: User.init)(
-  randomUuid.map(User.Id.init),
-  randomName,
-  randomEmail
-)
-
-//let randomUser = Gen {
-//  User(
-//    id: randomId.run(),
-//    name: randomName.run(),
-//    email: randomEmail.run()
-//  )
-//}
-
-print(randomUser.run())
-print(randomUser.run())
-print(randomUser.run())
-print(randomUser.run())
+print(try User(from: ArbitraryDecoder()))
+print(try User(from: ArbitraryDecoder()))
+print(try User(from: ArbitraryDecoder()))
+print(try User(from: ArbitraryDecoder()))

0031-arbitrary-pt1/Arbitrary.playground/Pages/02-exercises.xcplaygroundpage/Contents.swift

@@ -0,0 +1,20 @@
+/*:
+ # Decodable Randomness
+
+ ## Exercises
+
+ 1.) We skipped over the `allKeys` property of the `KeyedDecodingContainerProtocol`, but it's what's necessary to decode dictionaries of values. On initialization of the `KeyedDecodingContainer`, generate a random number of random `CodingKey`s to populate this property.
+
+ You'll need to return `true` from `contains(_ key: Key)`.
+
+ Decode a few random dictionaries of various decodable keys and values. What are some of the limitations of decoding dictionaries?
+ */
+// TODO
+/*:
+ 2.) Create a new `UnkeyedContainer` struct that conforms to the `UnkeyedContainerProtocol` and return it from the `unkeyedContainer()` method of `ArbitraryDecoder`. As with the `KeyedDecodingContainer`, you can delete the same `decode` methods and have them delegate to the `SingleValueContainer`.
+
+ The `count` property can be used to generate a randomly-sized container, while `currentIndex` and `isAtEnd` can be used to let the decoder know how far along it is. Generate a random `count`, default the `currentIndex` to `0`, and define `isAtEnd` as a computed property using these values. The `currentIndex` property should increment whenever `superDecoder` is called.
+
+ Decode a few random arrays of various decodable elements.
+ */
+// TODO

0031-arbitrary-pt1/Arbitrary.playground/contents.xcplayground

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='6.0' target-platform='macos' display-mode='raw' executeOnSourceChanges='false'>
+    <pages>
+        <page name='01-episode'/>
+        <page name='02-exercises'/>
+    </pages>
+</playground>

README.md

@@ -33,3 +33,4 @@ This repository is the home of code written on episodes of
 1. [An HTML DSL](0028-html-dsl)
 1. [DSLs vs. Templating Languages](0029-dsls-vs-templating-languages)
 1. [Composable Randomness](0030-composable-randomness)
+1. [Decodable Randomness](0031-arbitrary-pt1)