🚀 YO Language

YO — A Programming Language That Talks Like You

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📝 What is YO?

YO is a beginner-friendly, dynamic programming language designed to make coding intuitive and fun. Built from scratch in Python, it prioritizes readability with conversational syntax and color-coded, actionable error diagnostics. It offers nested environments for functions, an interactive REPL mode, and built-in standard libraries for math, text, and lists.

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⚙️ Quick Install

YO runs on Python 3.10+. To install the required dependencies (primarily for colorized formatting), run:

pip install colorama

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👋 Hello World

Create a file named hello.yo and add the following code:

make greeting = "Hello World!"
say greeting

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📋 Syntax Cheatsheet

1. Variables (make)

Declares a new variable. Reassign variables without the make keyword.

make name = "Yogesh"
name = "Yogesh Taparia"

2. Print Output (say)

Prints text or numbers to the console.

say "My name is " + name

3. Conditionals (when)

Executes code blocks based on conditions.

make age = 21
when age >= 18 {
    say "You are an adult"
} else {
    say "You are a minor"
}

4. Counted Loops (repeat)

Loops a block of code a specific number of times.

repeat 3 times {
    say "YO!"
}

5. List Loops (for each)

Iterates over elements in a list.

for each num in [1, 2, 3] {
    say num
}

6. Functions (task)

Declares reusable tasks with arguments and return statements.

task add(a, b) {
    return a + b
}

make sum = add(5, 10)
say sum

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🚀 Running YO

Run a Script

To run a .yo file, use the yo.py runner:

python yo.py myfile.yo
# OR
python yo.py run myfile.yo

Interactive REPL Mode

Running yo.py with no arguments boots up interactive mode:

python yo.py

YO v1.0 — Interactive Mode
Type 'exit' to quit, 'clear' to reset variables
yo> make x = 5
yo> say x
5
yo> exit

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📚 Standard Libraries

Load built-in standard libraries using the use keyword.

🧮 Math Library

Exposes: round, floor, ceil, power, sqrt, random, abs, min, max.

use math
say math.sqrt(25) # Outputs 5.0

🔤 Text Library

Exposes: upper, lower, length, reverse, has, trim, split, replace, starts_with, ends_with.

use text
say text.upper("hello") # Outputs HELLO

📋 List Library

Exposes: count, add, remove, sort, reverse, first, last, has, join.

use list
make my_list = [3, 1, 2]
say list.sort(my_list) # Outputs [1, 2, 3]

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📁 Project Structure

yo-lang/
├── stdlib/            # Standard Library Python modules
│   ├── list_lib.py    # List primitives
│   ├── math_lib.py    # Mathematical primitives
│   └── text_lib.py    # String primitives
├── tests/             # Sample YO scripts
│   ├── test1.yo       # Basics test
│   ├── test2.yo       # Functions and lists test
│   └── test3.yo       # Standard libraries test
├── environment.py     # Environment variable scope tracking
├── errors.py          # Color-coded error styling & formatting
├── interpreter.py     # AST execution engine
├── lexer.py           # Handwritten scanner & tokenizer
├── parser.py          # Handwritten recursive descent parser
├── README.md          # Project documentation
└── yo.py              # CLI & REPL entrypoint

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🔍 Error Messages: YO vs Python

YO was designed with beginner-friendly error messages to help first-time coders fix bugs faster. While Python stops at the first error with a traceback, YO collects multiple errors, suggests inline fixes (like typo corrections), and provides a built-in interactive explanation tool (yo explain).

See the full side-by-side comparison, design philosophy, and study results in comparison.md.

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🎓 Built By

• Yogesh Taparia - UEM Jaipur CSE

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📄 License

This project is licensed under the MIT License - see the LICENSE file for details.