add typestate typescript example

07-typestate-ts/main.ts

@@ -0,0 +1,30 @@
+type State = "locked" | "unlocked";
+
+class CredentialManager<S extends State> {
+  private readonly state?: S;
+
+  unlock(this: CredentialManager<"locked">, master_key: string) {
+    return this as unknown as CredentialManager<"unlocked">;
+  }
+
+  set(this: CredentialManager<"unlocked">, key: string, value: any) {
+    // ...
+  }
+
+  get(this: CredentialManager<"unlocked">, key: string): string | undefined {
+    // ...
+    return undefined;
+  }
+
+  lock(this: CredentialManager<"unlocked">): CredentialManager<"locked"> {
+    return this as unknown as CredentialManager<"locked">;
+  }
+}
+
+function main2() {
+  let pw_locked = new CredentialManager<"locked">();
+  let pw_unlocked = pw_locked.unlock("psst");
+  pw_unlocked.set("foo", "bar");
+  let val = pw_unlocked.get("foo");
+  pw_locked = pw_unlocked.lock();
+}

08-type-mapping/main.ts

@@ -30,7 +30,7 @@ class WebSocketClient {
   }
 }
 
-function main_ws() {
+function main1() {
   const client = new WebSocketClient();
   client.send(OpCode.PING, {});
 }

09-type-programming/main.ts

@@ -23,7 +23,7 @@ function navigate<P extends string>(path: P, params: ParseUrlParams<P>) {
   // ...
 }
 
-function main() {
+function main3() {
   navigate("/hello", {});
   navigate("/hello/{name}", { name: "foo" });
   navigate("/book/{author}/{id}", { author: "foo", id: "bar" });

Cargo.toml

@@ -1,2 +1,3 @@
 [workspace]
 members = ["01-problem", "02-runtime-check", "03-builder-pattern", "04-typestate"]
+resolver = "3"