protohackers/0.ts

import { copy } from "https://deno.land/std@0.156.0/streams/conversion.ts";

const PORT = 5588;

console.log(`Listening on port ${PORT}`);

for await (const conn of Deno.listen({ port: PORT })) {
  echo(conn);
}

async function echo(conn: Deno.Conn) {
  await copy(conn, conn);
  conn.close();
}