Prompt Engineering Lab

fix my code

Debug this Python function that should return the sum of even numbers in a list but returns 0 for [2, 4, 6]. Here's the code:

def sum_evens(nums):
    total = 0
    for n in nums:
        if n % 2 == 0:
            total += n
        return total

write a blog post

Write a 1200-word blog post about React Server Components for mid-level frontend developers. Tone: conversational but technical. Structure: intro hook with a pain point, 3 sections with descriptive subheadings, 2 code examples showing before/after, actionable conclusion with next steps.

explain kubernetes

Explain Kubernetes to a backend developer who uses Docker but hasn't worked with orchestration. Cover: what problems it solves, core concepts (pods, services, deployments), and a minimal example of deploying a Node.js app. Skip the history and comparison with Docker Swarm.

write tests for my function

Write Jest tests for this TypeScript function that validates email addresses. Cover: valid emails (user@domain.com), edge cases (plus addressing, subdomains), and invalid inputs (missing @, spaces, empty string). Use describe/it blocks with clear test names.

export function isValidEmail(email: string): boolean { ... }

review this code

Review this Express.js authentication middleware for: 1) Security vulnerabilities (especially JWT handling) 2) Error cases that return 500 instead of proper status codes 3) Race conditions with the database call. The code handles ~10K requests/minute in production.

write me a SQL query

Write a PostgreSQL query to find the top 10 customers by total order value in the last 30 days. Tables: customers (id, name, email), orders (id, customer_id, total, created_at). Include customers with no orders as $0. Format the output as: name, email, total_spent (descending).

make this code better

Refactor this React component to: 1) Extract the fetch logic into a custom hook 2) Replace the nested ternaries with early returns 3) Add proper TypeScript types (currently using 'any' in 4 places) 4) Memoize the expensive filter operation. Keep the component's behavior identical.

help me deploy my app

Create a GitHub Actions workflow to deploy a Next.js 14 app to AWS EC2. Requirements: run on push to main, build with Node 20, run tests first, SSH deploy to ec2-user@my-server, use PM2 for process management, send Slack notification on success/failure. Our secrets are in GitHub Secrets.

write a regex for phone numbers

Write a JavaScript regex to validate US phone numbers. Must accept: (123) 456-7890, 123-456-7890, 123.456.7890, 1234567890, +1 123 456 7890. Must reject: 123-45-6789 (too few digits), letters, numbers with country codes other than +1. Return named capture groups for area code, prefix, and line number.