Setting Up Python Environment

In the previous lesson, you learned what programming is and why Python is the ideal language to start with. Now it’s time to get hands-on and prepare your computer so you can write and execute Python code.

Don’t worry if you have no technical experience: I’ll explain step by step how to install everything you need. By the end of this lesson, you’ll have executed your first program.

What are we going to install?

To program in Python, you need three things:

1. Python (the language itself)
2. asdf (a version manager that makes Python installation easier)
3. VS Code (a professional and free code editor)

Why asdf?

You could install Python directly from python.org, but asdf is the professional way to manage Python versions (and other languages). It allows you to:

• Install multiple Python versions on your system
• Switch between versions easily
• Keep your system clean and organized

It’s what professional developers use, and the sooner you get used to it, the better.

Step 1: Installing asdf

On macOS or Linux

Open your terminal and execute these commands one by one:

# Clone the asdf repository
git clone https://github.com/asdf-vm/asdf.git ~/.asdf --branch v0.14.0

# Add asdf to your shell (bash)
echo '. "$HOME/.asdf/asdf.sh"' >> ~/.bashrc
echo '. "$HOME/.asdf/completions/asdf.bash"' >> ~/.bashrc

# If you use zsh instead of bash:
echo '. "$HOME/.asdf/asdf.sh"' >> ~/.zshrc
echo 'fpath=(${ASDF_DIR}/completions $fpath)' >> ~/.zshrc
echo 'autoload -Uz compinit && compinit' >> ~/.zshrc

Close and reopen your terminal for the changes to take effect.

Verify the installation:

asdf --version

You should see something like: v0.14.0

On Windows

On Windows, the easiest way is to use WSL (Windows Subsystem for Linux). WSL allows you to run Linux inside Windows, and it’s the standard way to develop in Python on Windows.

1. Open PowerShell as administrator and execute:

wsl --install

2. Restart your computer when prompted
3. Once restarted, an Ubuntu terminal will open. Set up a username and password
4. Now follow the macOS/Linux instructions above

Important note: Once you have WSL installed, you’ll always work from the Ubuntu terminal (not from PowerShell or CMD). It’s a complete Linux environment inside Windows.

Step 2: Installing Python with asdf

Now that you have asdf, let’s install Python. Execute these commands in your terminal:

# Add the Python plugin to asdf
asdf plugin add python

# Install Python 3.12 (latest stable version)
asdf install python 3.12.4

# Set Python 3.12.4 as the global version (asdf 0.18+)
asdf set --home python 3.12.4

The installation may take a few minutes. Be patient.

Verify the installation:

python --version

You should see: Python 3.12.4 (or the version you installed).

Also verify that pip (Python’s package manager) is available:

pip --version

Perfect. You now have Python running.

Step 3: Installing VS Code

VS Code (Visual Studio Code) is the world’s most popular code editor. It’s free, powerful, and has thousands of extensions.

Installation

1. Go to https://code.visualstudio.com/
2. Download the version for your operating system
3. Install like any other program

Configuration for Python

Once you have VS Code installed, install the official Python extension:

1. Open VS Code
2. Click the extensions icon (square with puzzle pieces) on the left sidebar
3. Search for “Python”
4. Install the Python extension by Microsoft (the one with the most downloads)

This extension provides you with:

• Syntax highlighting
• Intelligent autocomplete
• Real-time error detection
• Code execution from the editor

Step 4: Your first program

The moment has arrived. Let’s write your first Python program.

Create a file

1. Open VS Code
2. Create a folder for your Python projects (for example: ~/python-course)
3. Open that folder in VS Code: File > Open Folder
4. Create a new file: File > New File
5. Save it with the name hello.py (the .py extension indicates it’s a Python file)

Write the code

In the hello.py file, write:

print("Hello, World!")

Run the program

There are several ways to run Python code in VS Code:

Option 1: Integrated terminal

1. Open VS Code’s integrated terminal: View > Terminal (or Ctrl + ñ)
2. Execute: python hello.py

Option 2: Run button

1. Click the ▶️ (Play) button that appears in the top right corner
2. Select “Run Python File in Terminal”

You should see in the terminal:

Hello, World!

Congratulations! You’ve written and executed your first Python program.

Understanding print()

The code you just wrote is extremely simple, but there are important concepts:

print("Hello, World!")

• print() is a Python function that displays text on the screen
• "Hello, World!" is a string (text string) - it always goes in quotes
• The parentheses () are necessary to call the function

Let’s experiment a bit more. Modify your hello.py file:

print("Hello, World!")
print("Welcome to Python programming!")
print("This is my first program.")

Run again. You’ll see that each print() displays its text on a new line.

Testing with different texts

Now try this:

print("My name is [YOUR NAME]")
print("I am learning Python")
print("Python is awesome!")

Replace [YOUR NAME] with your actual name and run the program.

Common troubleshooting

”python: command not found”

If when running python --version it says the command is not found:

1. Verify that asdf is correctly installed: asdf --version
2. Verify that Python is installed: asdf list python
3. Make sure you’ve restarted the terminal after installing asdf

”SyntaxError” when running code

If you see an error like:

SyntaxError: invalid syntax

Check that:

• Quotes are correctly closed: "text"
• Parentheses are balanced: print(...)
• You haven’t forgotten any symbol

VS Code doesn’t find Python

If VS Code says it can’t find Python:

1. Open the Command Palette: Ctrl + Shift + P (or Cmd + Shift + P on Mac)
2. Search for “Python: Select Interpreter”
3. Select the Python version you installed with asdf

Note about asdf set --home vs asdf set

In this course we use asdf set --home python 3.12.4 to make Python available globally on your system. This creates a ~/.tool-versions file in your home folder.

If in the future you work on projects that need specific Python versions, you can use asdf set python X.Y.Z (without --home) inside the project directory. This creates a local .tool-versions file that only affects that project.

For this course, don’t worry about this. The global configuration is enough.

Summary

In this lesson you have:

✅ Installed asdf (professional version manager)
✅ Installed Python 3.12 with asdf
✅ Configured VS Code with the Python extension
✅ Written and executed your first Python program
✅ Learned to use the print() function

You now have everything you need to continue learning Python. In the next lesson, we’ll start with the fundamentals: variables and data types.

Practical exercise

Before continuing, make sure your environment works correctly:

1. Create a new file called test.py
2. Write a program that displays 5 lines of text with information about you (name, city, hobby, etc.)
3. Run the program and verify that everything works

Example expected output:

My name is Alice
I live in Madrid
I love playing guitar
I am 25 years old
I want to become a Python developer

If you’ve managed to run this program without errors, you’re ready for the next lesson.