merilang 1.0.2

A desi toy programming language built with Python

MeriLang 🇮🇳

A desi toy programming language built with Python.

Features ✨

• Simple Syntax: Easy-to-learn syntax with meri keywords
• Full Programming Language: Variables, functions, loops, conditionals, and more
• Object-Oriented Programming: Classes, inheritance, methods, and properties
• Error Handling: Try-catch-finally blocks for robust error management
• Interactive REPL: Test code snippets interactively
• Helpful Error Messages: Clear error messages with line numbers
• Built-in Functions: Rich standard library for common operations
• File I/O: Read and write files
• Module System: Import and reuse code across files
• Web Playground: Browser-based code editor and runner

Installation 📦

Using pip (Recommended)

pip install merilang

From Source

git clone https://github.com/XploitMonk0x01/merilang.git
cd merilang
pip install -e .

Quick Start 🚀

Hello World

Create a file hello.meri:

shuru
dikhao "Hello, World!"
khatam

Run it:

merilang hello.meri
# or
ml hello.meri

Interactive REPL

merilang
# or
ml

MeriLang v1.0.1 Interactive REPL
Type 'exit' or press Ctrl+C to quit

>>> x = 42
>>> dikhao x
42
>>> dikhao x * 2
84

Language Syntax 📝

Program Structure

Every MeriLang program starts with shuru (begin) and ends with khatam (end):

shuru
// Your code here
khatam

Comments

// Single-line comments start with //

Variables

shuru
x = 42              // Integer
pi = 3.14           // Float
naam = "Rajwant"    // String
is_valid = sahi     // Boolean (true)
is_false = galat    // Boolean (false)
khatam

Data Types

• Numbers: 42, 3.14
• Strings: "Hello", "नमस्ते"
• Booleans: sahi (true), galat (false)
• Lists: [1, 2, 3], ["a", "b", "c"]

Operators

Arithmetic:

• + Addition
• - Subtraction
• * Multiplication
• / Division
• % Modulo

Comparison:

• > Greater than
• < Less than
• >= Greater than or equal
• <= Less than or equal
• == Equal to
• != Not equal to

Print Statement

shuru
dikhao "Hello"      // Print string
dikhao 42           // Print number
dikhao x            // Print variable
dikhao x + y        // Print expression
khatam

Input

shuru
dikhao "Enter your name:"
padho naam
dikhao "Hello, " + naam
khatam

Conditionals

shuru
age = 25

agar age >= 18 {
    dikhao "Adult"
} warna {
    dikhao "Minor"
} bas
khatam

Loops

For Loop:

shuru
chalao i se 0 tak 5 {
    dikhao i
}
khatam

While Loop:

shuru
count = 0
jabtak count < 5 {
    dikhao count
    count = count + 1
} band
khatam

Functions

shuru
// Function definition
vidhi add(a, b) {
    vapas a + b
} samapt

// Function call
result = add(5, 3)
dikhao result

// Or use bulayo keyword
bulayo add(10, 20)
khatam

Lists

shuru
// Create list
numbers = [1, 2, 3, 4, 5]

// Access element
dikhao numbers[0]

// Modify element
numbers[1] = 99

// Add element
append(numbers, 6)

// List operations
dikhao length(numbers)
dikhao sum(numbers)
dikhao max(numbers)
dikhao min(numbers)

sorted_nums = sort(numbers)
reversed_nums = reverse(numbers)
khatam

Built-in Functions

List Operations:

• length(list) - Get length
• append(list, value) - Add element
• pop(list, index) - Remove and return element
• insert(list, index, value) - Insert at index
• sort(list) - Return sorted copy
• reverse(list) - Return reversed copy
• sum(list) - Sum all elements
• min(list/args) - Get minimum
• max(list/args) - Get maximum

String Operations:

• upper(string) - Convert to uppercase
• lower(string) - Convert to lowercase
• split(string, separator) - Split into list
• join(list, separator) - Join list into string
• replace(string, old, new) - Replace substring

Type Operations:

• type(value) - Get type name
• str(value) - Convert to string
• int(value) - Convert to integer
• float(value) - Convert to float

I/O Operations:

• input(prompt) - Read user input
• likho "file.txt" content - Write to file
• padho_file("file.txt") - Read from file

File I/O

shuru
// Write to file
likho "output.txt" "Hello, MeriLang!"

// Read from file
content = padho_file("output.txt")
dikhao content
khatam

Importing Modules

// mylib.meri
shuru
vidhi helper_function(x) {
    vapas x * 2
} samapt
khatam

// main.meri
shuru
lao "mylib"
result = helper_function(21)
dikhao result
khatam

Object-Oriented Programming

shuru

// Define a class
class Person {
    vidhi __init__(naam, umar) {
        yeh.naam = naam
        yeh.umar = umar
    }
    samapt

    vidhi greet() {
        dikhao "Namaste, "
        dikhao yeh.naam
    }
    samapt
}

// Create instance
p = naya Person("Rajesh", 25)
p.greet()

// Access property
dikhao p.naam

// Inheritance
class Student badhaao Person {
    vidhi __init__(naam, umar, school) {
        yeh.naam = naam
        yeh.umar = umar
        yeh.school = school
    }
    samapt

    vidhi study() {
        dikhao yeh.naam
        dikhao " is studying"
    }
    samapt
}

s = naya Student("Priya", 20, "Delhi University")
s.greet()      // Inherited method
s.study()      // Own method

khatam

Error Handling

shuru

// Try-catch-finally
koshish {
    x = 10 / 0  // This will fail
}
pakdo err {
    dikhao "Error: "
    dikhao err
}
akhir {
    dikhao "Cleanup done"
}

// Throw custom exceptions
vidhi validate_age(age) {
    agar age < 0 {
        fenko "Age cannot be negative"
    }
    bas
    vapas sahi
}
samapt

koshish {
    validate_age(-5)
}
pakdo err {
    dikhao "Validation error: "
    dikhao err
}

khatam

Examples 📚

See the examples directory for complete programs:

Basic Examples

1. Hello World
2. Variables
3. Conditionals
4. Loops
5. Functions
6. FizzBuzz
7. Fibonacci
8. Lists
9. Prime Numbers
10. String Operations

Advanced Examples (OOP & Error Handling)

11. Basic Class - Class definition and objects
12. Inheritance - Class inheritance with badhaao
13. Bank Account - Real-world OOP example
14. Error Handling - Try-catch-finally patterns
15. Complete OOP + Errors - Advanced combination

CLI Usage 💻

# Run a script
merilang script.meri
# or use short alias
ml script.meri

# Start REPL (interactive mode)
merilang
ml

# Show version
merilang --version
ml --version

# Show help
merilang --help
ml --help

Development 🛠️

Running Tests

# Install development dependencies
pip install pytest

# Run all tests
pytest tests/

# Run with coverage
pytest tests/ --cov=MeriLang --cov-report=html

# Run specific test file
pytest tests/test_lexer.py -v

Project Structure

merilang/
├── merilang/              # Main package
│   ├── __init__.py
│   ├── lexer_enhanced.py  # Tokenizer
│   ├── parser_enhanced.py # Parser
│   ├── ast_nodes_enhanced.py # AST node definitions
│   ├── interpreter_enhanced.py # Interpreter
│   ├── environment.py     # Environment management
│   ├── errors_enhanced.py # Error classes
│   └── cli.py            # Command-line interface
├── tests/                # Comprehensive test suite (172+ tests)
│   ├── test_lexer_enhanced.py
│   ├── test_parser_enhanced.py
│   ├── test_interpreter_enhanced.py
│   ├── test_oop.py
│   ├── test_error_handling.py
│   └── test_integration.py
├── examples/             # 25+ example programs (.meri files)
├── benchmarks/           # Performance benchmarks
├── docs/                # Documentation
│   ├── TUTORIAL.md      # Comprehensive tutorial
│   └── API.md           # API documentation
└── pyproject.toml       # Package configuration

Keyword Reference 🔤

English	MeriLang	Usage
Begin	shuru	Program start
End	khatam	Program end
Print	dikhao	Output statement
Input	padho	Read input
If	agar	Conditional
Else	warna	Alternative branch
End If	bas	Close if block
While	jabtak	While loop
End While	band	Close while loop
For	chalao	For loop
From	se	Loop start
To	tak	Loop end
Function	vidhi	Define function/method
Return	vapas	Return value
End Function	samapt	Close function
Call	bulayo	Call function
True	sahi	Boolean true
False	galat	Boolean false
Import	lao	Import module
Write	likho	Write to file
Class	class	Define class
New	naya	Create object
This	yeh	Current instance
Extends	badhaao	Inherit from class
Super	upar	Call parent method
Try	koshish	Try block
Catch	pakdo	Catch exception
Finally	akhir	Finally block
Throw	fenko	Throw exception

Error Handling 🚨

MeriLang provides helpful error messages with line numbers:

Line 5, Column 12: Undefined variable: 'xyz'
Line 8: Division by zero
Line 12: Expected '=' after identifier

You can also handle errors gracefully with try-catch:

koshish {
    risky_operation()
}
pakdo err {
    dikhao "Error handled: "
    dikhao err
}

Documentation 📖

🌐 Official Documentation Website

For comprehensive guides, see:

• TUTORIAL.md - Complete beginner-friendly tutorial
• API.md - API documentation and advanced features
• QUICKSTART.md - Quick start guide
• CONTRIBUTING.md - Contribution guidelines

Contributing 🤝

Contributions are welcome! Please feel free to submit a Pull Request.

1. Fork the repository
2. Create your feature branch (git checkout -b feature/AmazingFeature)
3. Commit your changes (git commit -m 'Add some AmazingFeature')
4. Push to the branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

License 📄

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

Roadmap 🗺️

• Full lexer and parser
• Interpreter with scopes
• Functions and recursion
• Lists and data structures
• File I/O and modules
• Object-Oriented Programming (classes, inheritance, methods)
• Error handling (try-catch-finally, exceptions)
• Comprehensive test suite
• CLI and REPL
• Web playground
• Documentation website
• Package manager
• Debugger with breakpoints
• Standard library expansion
• IDE extensions (VS Code, etc.)
• Compiled mode (faster execution)

Credits 💖

Inspired by educational programming languages and the need for culturally relevant learning tools.

Support ⭐

If you like MeriLang, please give it a star on GitHub!

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Made with ❤️ for the meri community