2023-09-19T09:52:58.562Z

src/065-types-you-dont-control/174-definitely-typed.problem/helpers.d.ts

@@ -0,0 +1,17 @@
+type Expect<T extends true> = T;
+type Equal<X, Y> = (<T>() => T extends X ? 1 : 2) extends <T>() => T extends Y
+  ? 1
+  : 2
+  ? true
+  : false;
+
+/**
+ * Checks that Y is assignable to X.
+ *
+ * For instance, `Extends<string, 'a'>` is true. This is because
+ * 'a' can be passed to a function which expects a string.
+ *
+ * But `Extends<'a', string>` is false. This is because a string
+ * CANNOT be passed to a function which expects 'a'.
+ */
+type Extends<X, Y> = Y extends X ? true : false;

src/065-types-you-dont-control/174-definitely-typed.problem/package.json

@@ -0,0 +1,12 @@
+{
+  "name": "exercise",
+  "version": "1.0.0",
+  "main": "index.js",
+  "type": "module",
+  "scripts": {
+    "dev": "tsc --watch"
+  },
+  "dependencies": {
+    "diff": "^5.1.0"
+  }
+}

src/065-types-you-dont-control/174-definitely-typed.problem/src/index.ts

@@ -0,0 +1,19 @@
+import Diff from "diff";
+
+const message = "Hello, world!";
+
+const secondMessage = "Goodbye, world!";
+
+const diff = Diff.diffChars(message, secondMessage);
+
+type test = Expect<
+  Equal<
+    typeof diff,
+    {
+      count?: number;
+      value: string;
+      added?: boolean;
+      removed?: boolean;
+    }[]
+  >
+>;

src/065-types-you-dont-control/174-definitely-typed.problem/tsconfig.json

@@ -0,0 +1,15 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext",
+    "esModuleInterop": true,
+    "outDir": "dist",
+    "rootDir": "src",
+    "strict": true,
+    "skipLibCheck": true,
+    "isolatedModules": true,
+    "moduleDetection": "force",
+    "verbatimModuleSyntax": true
+  },
+}

src/065-types-you-dont-control/174-definitely-typed.solution/helpers.d.ts

@@ -0,0 +1,17 @@
+type Expect<T extends true> = T;
+type Equal<X, Y> = (<T>() => T extends X ? 1 : 2) extends <T>() => T extends Y
+  ? 1
+  : 2
+  ? true
+  : false;
+
+/**
+ * Checks that Y is assignable to X.
+ *
+ * For instance, `Extends<string, 'a'>` is true. This is because
+ * 'a' can be passed to a function which expects a string.
+ *
+ * But `Extends<'a', string>` is false. This is because a string
+ * CANNOT be passed to a function which expects 'a'.
+ */
+type Extends<X, Y> = Y extends X ? true : false;

src/065-types-you-dont-control/174-definitely-typed.solution/package.json

@@ -0,0 +1,15 @@
+{
+  "name": "exercise",
+  "version": "1.0.0",
+  "main": "index.js",
+  "type": "module",
+  "scripts": {
+    "dev": "tsc --watch"
+  },
+  "dependencies": {
+    "diff": "^5.1.0"
+  },
+  "devDependencies": {
+    "@types/diff": "^5.0.4"
+  }
+}

src/065-types-you-dont-control/174-definitely-typed.solution/src/index.ts

@@ -0,0 +1,19 @@
+import Diff from "diff";
+
+const message = "Hello, world!";
+
+const secondMessage = "Goodbye, world!";
+
+const diff = Diff.diffChars(message, secondMessage);
+
+type test = Expect<
+  Equal<
+    typeof diff,
+    {
+      count?: number;
+      value: string;
+      added?: boolean;
+      removed?: boolean;
+    }[]
+  >
+>;

src/065-types-you-dont-control/174-definitely-typed.solution/tsconfig.json

@@ -0,0 +1,15 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext",
+    "esModuleInterop": true,
+    "outDir": "dist",
+    "rootDir": "src",
+    "strict": true,
+    "skipLibCheck": true,
+    "isolatedModules": true,
+    "moduleDetection": "force",
+    "verbatimModuleSyntax": true
+  },
+}