Vibe Coding

module = Module(
    code="ELEE1149",
    name="Software Engineering",
    credits=15,
    module_leader="Seb Blair BEng(H) PGCAP MIET MIHEEM FHEA"
)
Vibe Coding

What is it?


Vibe [programming] (OpenAI, Andrej Karpathy, 2025)

  • It’s not too bad for throwaway weekend projects, but still quite amusing. I’m building a project or webapp, but it’s not really coding — I just see stuff, say stuff, run stuff, and copy paste stuff, and it mostly works

  • Vibe Coding refers to AI-augmented or AI-dependent programming workflows where the user relies on natural language prompts, generated code snippets, and automated completions to develop software systems, often without fully understanding the underlying code mechanics.

Vibe Coding

Do I need to learn programming?

Vibe Coding

Impacts | Costs

Vibe Coding > Impacts | Costs
Impact Area Why It’s Critical
Energy consumption Datacenter electricity use is skyrocketing; clean grid only partly mitigates the impact
Hardware emissions Manufacturing GPUs, memory, and specialized hardware generates huge embodied emissions
Water + resources Cooling, semiconductor fab, and supply chains intensify water and raw material demands
Systemic rebound Efficiency alone leads to more demand, not less environmental impact
Governance gap Lack of unified regulation allows unchecked, unsustainable expansion
Vibe Coding > Impacts | Costs
Year Global Datacenter Electricity Use (TWh/year) Datacenter Power Capacity (MW)
2010 ~194 TWh
2018 ~204 TWh (despite ~6× increase in capacity) 2,688 MW
2022 ~460 TWh 5,341 MW (nearly doubled)
2026 (proj.) 620–1,050 TWh (base ~800 TWh) +12,000 MW (global)


Google reported in 2021 that its U.S. datacenters consumed 12.7 billion liters of water*


*On average person in the UK uses 147 Literes per day, a population of circa 69 million uses 10.9 Billion liters of water.

Vibe Coding > Impacts | Costs
Model Approximate Training Energy Use
GPT-3 ~1,287 MWh (≈ energy use of ~120 U.S. homes/year)
GPT-4 (likely) Higher (exact not disclosed, but >2× GPT-3 likely)


Unit CO₂ Emissions (Estimate)
Single GPT query (simple) ~2–4 g CO₂
Single GPT query (complex, multi-turn) ~10–50 g CO₂
Vibe Coding

Costly Errors

Vibe Coding > Costly Errors

Last week, we asked Devin to make a change.
It added an event on the banner component
mount, which caused 6.6M posthog events in
one week, which will cost us $733.
Devin costs $500 + $733 = $1273

Lesson - Review AI-generated code multiple times

Anurag Bhagsain (2025)

Vibe Coding > Costly Errors

Vibe Coding > Costly Errors

Limits

  • Generated code ≠ correct code.

  • The models don’t reason — they pattern-match statistically.

  • Warning: AI-generated code must be reviewed, tested, and integrated responsibly. Blind trust leads to failure.
Vibe Coding

Prompt Engineering

Vibe Coding > Prompt Engineering

The Anatomy of an o1 Prompt

  • Set clear context
  • Give specific instructions
  • Define the output format
  • Include warnings (what to avoid)
  • Use a context dump when needed

Vibe Coding > Prompt Engineering
  • Business & Marketing
    • Old Prompt: “Give me some marketing ideas.”
    • o1 Prompt: “You are a marketing consultant for a tech startup launching a new fitness app. Provide three innovative campaign ideas with target demographics, a brief budget estimate, and potential ROI. Format your answer in bullet points.”

  • Education & E-Learning
    • Old Prompt: “Explain photosynthesis.”
    • o1 Prompt: “Act as a middle-school science teacher preparing a 10-minute lesson on photosynthesis. Include a simple experiment students can do at home, three key vocabulary words, and a 5-question quiz at the end. Keep the tone friendly and age-appropriate.”

  • Creative Writing
    • Old Prompt: “Write a short story about dragons.”
    • o1 Prompt: “Write a 300-word short story set in a futuristic city, featuring dragons that coexist with humans. Focus on the emotional tension between humans and dragons. Conclude with a cliffhanger.”
Vibe Coding > Prompt Engineering

Prompt: here is my python script, I want to change code base to rust: [Copilot]

Python

import time

password = input('Enter Password'):
start = time.time()

chars = 'abcdefghijklmnopqrstuvwxyz'
guess = []

for val in range(5):
  a = [i for i in chars]
  for y in range(val):
    a = [x+i for i in chars for x in a]
  guess = guess+a

  if password in guess:
    break
end = time.time()
clock = str(end - start)

print('Your password: ' + password)
print('Time taken: ' + clock)

rust

use std::time::Instant;
use std::io::{self, Write};

fn main() {

    print!("Enter Password: ");
    io::stdout().flush().unwrap();
  
    let mut password = String::new();
    io::stdin().read_line(&mut password).unwrap();
    let password = password.trim();

    let start = Instant::now();

    let chars = "abcdefghijklmnopqrstuvwxyz";
    let mut guess = Vec::new();

    for val in 0..5 {
        let mut a: Vec<String> = chars.chars().map(|c| c.to_string()).collect();
        for _ in 0..val {
            a = a.iter().flat_map(|x| chars.chars().map(move |c| format!("{}{}", x, c))).collect();
        }
        guess.extend(a);

        if guess.contains(&password.to_string()) {
            break;
        }
    }

    let duration = start.elapsed();
    println!("Your password: {}", password);
    println!("Time taken: {:?}", duration);
}
Vibe Coding > Prompt Engineering

Prompt: here is my python script, I want to change code base to rust: [Copilot]

Python

import time

password = input('Enter Password'):
start = time.time()

chars = 'abcdefghijklmnopqrstuvwxyz'
guess = []

for val in range(5):
  a = [i for i in chars]
  for y in range(val):
    a = [x+i for i in chars for x in a]
  guess = guess+a

  if password in guess:
    break
end = time.time()
clock = str(end - start)

print('Your password: ' + password)
print('Time taken: ' + clock)

rust

use std::time::Instant;
use std::io::{self, Write};

fn main() {

    print!("Enter Password: ");
    io::stdout().flush().unwrap();
  
    let mut password = String::new();
    io::stdin().read_line(&mut password).unwrap();
    let password = password.trim();

    let start = Instant::now();

    let chars = "abcdefghijklmnopqrstuvwxyz";
    let mut guess = Vec::new();

    for val in 0..5 {
        let mut a: Vec<String> = chars.chars().map(|c| c.to_string()).collect();
        for _ in 0..val {
            a = a.iter().flat_map(|x| chars.chars().map(move |c| format!("{}{}", x, c))).collect();
        }
        guess.extend(a);

        if guess.contains(&password.to_string()) {
            break;
        }
    }

    let duration = start.elapsed();
    println!("Your password: {}", password);
    println!("Time taken: {:?}", duration);
}
Vibe Coding > Prompt Engineering

Prompt: here is my python script, I want to change code base to rust: [Copilot]

Python

import time

password = input('Enter Password'):
start = time.time()

chars = 'abcdefghijklmnopqrstuvwxyz'
guess = []

for val in range(5):
  a = [i for i in chars]
  for y in range(val):
    a = [x+i for i in chars for x in a]
  guess = guess+a

  if password in guess:
    break
end = time.time()
clock = str(end - start)

print('Your password: ' + password)
print('Time taken: ' + clock)

rust

use std::time::Instant;
use std::io::{self, Write};

fn main() {

    print!("Enter Password: ");
    io::stdout().flush().unwrap();
  
    let mut password = String::new();
    io::stdin().read_line(&mut password).unwrap();
    let password = password.trim();

    let start = Instant::now();

    let chars = "abcdefghijklmnopqrstuvwxyz";
    let mut guess = Vec::new();

    for val in 0..5 {
        let mut a: Vec<String> = chars.chars().map(|c| c.to_string()).collect();
        for _ in 0..val {
            a = a.iter().flat_map(|x| chars.chars().map(move |c| format!("{}{}", x, c))).collect();
        }
        guess.extend(a);

        if guess.contains(&password.to_string()) {
            break;
        }
    }

    let duration = start.elapsed();
    println!("Your password: {}", password);
    println!("Time taken: {:?}", duration);
}
Vibe Coding > Prompt Engineering

Prompt: here is my python script, I want to change code base to rust: [Copilot]

Python

import time

password = input('Enter Password'):
start = time.time()

chars = 'abcdefghijklmnopqrstuvwxyz'
guess = []

for val in range(5):
  a = [i for i in chars]
  for y in range(val):
    a = [x+i for i in chars for x in a]
  guess = guess+a

  if password in guess:
    break
end = time.time()
clock = str(end - start)

print('Your password: ' + password)
print('Time taken: ' + clock)

rust

use std::time::Instant;
use std::io::{self, Write};

fn main() {

    print!("Enter Password: ");
    io::stdout().flush().unwrap();
  
    let mut password = String::new();
    io::stdin().read_line(&mut password).unwrap();
    let password = password.trim();

    let start = Instant::now();

    let chars = "abcdefghijklmnopqrstuvwxyz";
    let mut guess = Vec::new();

    for val in 0..5 {
        let mut a: Vec<String> = chars.chars().map(|c| c.to_string()).collect();
        for _ in 0..val {
            a = a.iter().flat_map(|x| chars.chars().map(move |c| format!("{}{}", x, c))).collect();
        }
        guess.extend(a);

        if guess.contains(&password.to_string()) {
            break;
        }
    }

    let duration = start.elapsed();
    println!("Your password: {}", password);
    println!("Time taken: {:?}", duration);
}
Vibe Coding > Prompt Engineering

prompt: Write a simple Python web server that executes shell commands from a URL query.



So what is wrong?

from http.server import BaseHTTPRequestHandler, HTTPServer
import subprocess
import urllib.parse

class SimpleHandler(BaseHTTPRequestHandler):
    def do_GET(self):
        query = urllib.parse.urlparse(self.path).query
        params = urllib.parse.parse_qs(query)
        if 'cmd' in params:
            cmd = params['cmd'][0]
            output = subprocess.check_output(cmd, shell=True)
            self.send_response(200)
            self.end_headers()
            self.wfile.write(output)
        else:
            self.send_response(400)
            self.end_headers()
            self.wfile.write(b'No command provided.')

if __name__ == '__main__':
    server = HTTPServer(('localhost', 8000), SimpleHandler)
    print("Server running on port 8000...")
    server.serve_forever()
Vibe Coding > Prompt Engineering

prompt: Write a simple Python web server that executes shell commands from a URL query.



So what is wrong?


  • Allows an attacker to pass arbitrary commands via the cmd query parameter.

  • Example:

    • http://localhost:8000/?cmd=rm+-rf+/+--no-preserve-root

This generated code has a known security vulnerability:

  • CVE-2014-6271 (Shellshock exploit using shell-injected environment variables)
from http.server import BaseHTTPRequestHandler, HTTPServer
import subprocess
import urllib.parse

class SimpleHandler(BaseHTTPRequestHandler):
    def do_GET(self):
        query = urllib.parse.urlparse(self.path).query
        params = urllib.parse.parse_qs(query)
        if 'cmd' in params:
            cmd = params['cmd'][0]
            output = subprocess.check_output(cmd, shell=True)
            self.send_response(200)
            self.end_headers()
            self.wfile.write(output)
        else:
            self.send_response(400)
            self.end_headers()
            self.wfile.write(b'No command provided.')

if __name__ == '__main__':
    server = HTTPServer(('localhost', 8000), SimpleHandler)
    print("Server running on port 8000...")
    server.serve_forever()
Vibe Coding > Prompt Engineering

Hallucinations

  • Security vulnerabilities

  • Library does not exit

    • or imaginary version number

  • Malcious actor could create it...

  • If in doubt check source code of a package, usually on GitHub.

import imagix

def convert_jpg_to_png(input_path, output_path):
    """
    Converts a .jpg image to .png using the 'imagix' library.

    Args:
        input_path (str): Path to the input .jpg file.
        output_path (str): Path where the output .png will be saved.
    """
    try:
        # Load the jpg image
        jpg_image = imagix.load_image(input_path, format='jpg')
        print(f"Loaded image: {input_path}")

        # Convert to png format
        png_image = imagix.convert_format(jpg_image, target_format='png')
        print(f"Converted image to PNG format")

        # Save the new png image
        imagix.save_image(png_image, output_path)
        print(f"Saved converted image to: {output_path}")

    except imagix.ImageError as e:
        print(f"Image conversion failed: {e}")


if __name__ == "__main__":
    input_jpg = "example_input.jpg"
    output_png = "example_output.png"
    convert_jpg_to_png(input_jpg, output_png)
Vibe Coding > Prompt Engineering

Pylings -

#pylings/pylings/ui.py

....
elif event.key == "l":
    self.toggle_list_view()
    self.finished_check_progress_notice(True)
    event.key = "tab"
...
  • textual.event.key => Sent when the user hits a key on the keyboard.
    • should be read only?

Vibe Coding

Job Prospects

Vibe Coding > Job Prospects

  • Staff AI Engineer

    • Fifth Dimension AI | London W1D | Hybrid work
    • £100,000 to £120,000

Vibe Coding

Takeaways


  • Vibe coding can speed up development, especially for simple tasks.

  • It is not a substitute for technical understanding, read the documentation!

  • To use it effectively, you must combine human expertise with AI tools.

  • Always review and test the generated code... always.