Add example: Collections

Author: Artem Tyurin

examples/collections/collections.kt

@@ -0,0 +1,19 @@
+enum class Food {
+  vegetable,
+  fruit,
+  fastfood
+}
+
+val farm = hashMapOf(
+  Food.vegetable to setOf("🍅", "🌽"),
+  Food.fruit to setOf("🍌", "🍏")
+)
+
+fun main() {
+  val vegetables = farm[Food.vegetable]
+  if (vegetables != null) {
+    if (vegetables.contains("🍅")) {
+      println("We have tomatoes!")
+    }
+  }
+}

examples/collections/collections.rs

@@ -0,0 +1,31 @@
+use std::collections::HashMap;
+use std::collections::HashSet;
+
+#[derive(Hash, PartialEq, Eq)]
+enum Food {
+  Vegetable,
+  Fruit,
+  FastFood,
+}
+
+fn main() {
+  let mut vegetables = HashSet::new();
+  vegetables.insert("🍅");
+  vegetables.insert("🌽");
+
+  let mut fruits = HashSet::new();
+  fruits.insert("🍌");
+  fruits.insert("🍏");
+
+  let mut farm = HashMap::new();
+  farm.insert(Food::Vegetable, vegetables);
+  farm.insert(Food::Fruit, fruits);
+
+  if let Some(vegetables) =
+    farm.get(&Food::Vegetable)
+  {
+    if vegetables.contains("🍅") {
+      println!("We have tomatoes!");
+    }
+  }
+}

examples/collections/collections.swift

@@ -0,0 +1,16 @@
+enum Food {
+  case vegetable
+  case fruit
+  case fastfood
+}
+
+var farm: [Food:Set<String>] = [
+  .vegetable: Set(["🍅", "🌽"]),
+  .fruit: Set(["🍌", "🍏"])
+]
+
+if let vegetables = farm[.vegetable] {
+  if (vegetables.contains("🍅")) {
+    print("We have tomatoes!")
+  }
+}

examples/collections/collections.ts

@@ -0,0 +1,17 @@
+enum Food {
+  vegetable,
+  fruit,
+  fastfood
+}
+
+const farm = new Map([
+  [Food.vegetable, new Set(["🍅", "🌽"])],
+  [Food.fruit, new Set(["🍌", "🍏"])]
+]);
+
+const vegetables = farm.get(Food.vegetable);
+if (vegetables) {
+  if (vegetables.has("🍅")) {
+    console.log("We have tomatoes!");
+  }
+}

src/examples.ts

@@ -45,6 +45,32 @@ export const examples: Example[] = [
       )
     }
   },
+  {
+    key: "collections",
+    title: "Collections",
+    code: {
+      swift: readFileSync(
+        __dirname +
+          "/../examples/collections/collections.swift",
+        "utf-8"
+      ),
+      kotlin: readFileSync(
+        __dirname +
+          "/../examples/collections/collections.kt",
+        "utf-8"
+      ),
+      typescript: readFileSync(
+        __dirname +
+          "/../examples/collections/collections.ts",
+        "utf-8"
+      ),
+      rust: readFileSync(
+        __dirname +
+          "/../examples/collections/collections.rs",
+        "utf-8"
+      )
+    }
+  },
   {
     key: "higher-order-functions",
     title: "Higher-order functions",

src/playground.ts

@@ -3,7 +3,11 @@ import * as LZString from "lz-string";
 export const playground = {
   kotlin: (code: string) =>
     `https://play.kotlinlang.org/#${btoa(
-      JSON.stringify({ code })
+      unescape(
+        encodeURIComponent(
+          JSON.stringify({ code })
+        )
+      )
     )}`,
 
   swift: (code: string) =>