metabuilder/mojo/samples

Mojo Language Examples

Reference implementations and tutorials for the Mojo programming language.

Quick Start

cd mojo
pixi install
pixi run main  # Run samples/src/main.mojo

Sample Programs

Game of Life

Three different implementations of Conway's Game of Life showing optimization strategies:

cd samples/game-of-life
pixi run lifev1  # Basic implementation
pixi run lifev2  # Optimized memory
pixi run lifev3  # Fully optimized

Features:

• Grid data structures
• Neighbor calculations
• Simulation loop
• Performance optimization techniques

Snake Game

Full interactive game using SDL3 with FFI bindings:

cd samples/snake
pixi run snake

Features:

• C library integration (SDL3)
• Event handling
• Graphics rendering
• Game state management

GPU Functions

High-performance GPU kernels:

cd samples/gpu-functions
pixi run gpu-intro        # Simple vector addition
pixi run vector_add       # Advanced GPU kernels
pixi run matrix_mult      # GPU matrix multiplication
pixi run mandelbrot       # GPU Mandelbrot set
pixi run reduction        # GPU reduction operations

Features:

• Device memory management
• Kernel execution
• Block and thread organization
• Synchronization

Python Interoperability

Calling Mojo from Python and vice versa:

cd samples/python-interop
pixi run hello            # Export Mojo module to Python
pixi run mandelbrot       # Performance comparison
pixi run person           # Object interop

Features:

• Python module export
• Python object marshalling
• Performance optimization
• Bidirectional calls

Custom Operators

Implementing the Complex number type with operator overloading:

cd samples/operators
pixi run my_complex       # Complex arithmetic
pixi run test_complex     # Unit tests

Features:

• Struct definition
• Operator overloading (add, mul, etc.)
• Trait implementation
• Unit testing

Testing Framework

Demonstration of the Mojo testing framework:

cd samples/testing
pixi run test_math        # Run math tests

Features:

• TestSuite class
• Assert functions
• Test organization
• Result reporting

Tensor Operations

Using LayoutTensor for dense multidimensional arrays:

cd samples/layout_tensor
pixi run tensor_ops       # Tensor operations

Features:

• Dense array layout
• Efficient indexing
• Memory management
• GPU acceleration

Process Handling

OS process execution and management:

cd samples/process
pixi run process_demo     # Process execution

Features:

• Process spawning
• Standard I/O
• Exit codes
• Synchronization

Learning Path

Beginner:

1. Start with src/main.mojo - Basic syntax
2. Try operators/my_complex.mojo - Structs and operators
3. Explore game-of-life/gridv1.mojo - Algorithms

Intermediate:

1. Study game-of-life/ optimizations
2. Learn gpu-intro/ for GPU programming
3. Try python-interop/hello_mojo.mojo for integration

Advanced:

1. GPU kernels in gpu-functions/
2. Snake game with FFI in snake/
3. Custom tensors in layout_tensor/

Key Language Features Demonstrated

Feature	Location	Difficulty
Structs	operators/	Basic
Operators	operators/	Basic
Traits	operators/	Intermediate
Generics	gpu-functions/	Advanced
GPU Kernels	gpu-functions/	Advanced
FFI Bindings	snake/	Advanced
Python Interop	python-interop/	Advanced
Async/Await	(coming soon)	Advanced

Common Patterns

Struct Definition

struct Point:
    x: Float32
    y: Float32

    fn magnitude(self) -> Float32:
        return sqrt(self.x * self.x + self.y * self.y)

Trait Implementation

trait Drawable:
    fn draw(self):
        ...

struct Circle:
    radius: Float32

    fn draw(self):
        # Draw circle
        pass

GPU Kernel

fn gpu_add_kernel[blockSize: Int](
    output: DeviceBuffer,
    a: DeviceBuffer,
    b: DeviceBuffer,
):
    let idx = global_idx(0)
    if idx < len(output):
        output[idx] = a[idx] + b[idx]

Python Module Export

@export
fn mandelbrot_set(width: Int, height: Int) -> List[Complex]:
    # Compute Mandelbrot set
    return results

# Use from Python:
# from hello_mojo import mandelbrot_set

Running Tests

# Run all example tests
cd samples
pixi run test

# Run specific example tests
cd game-of-life
pixi run test

Performance Tips

1. Use SIMD for vectorizable loops
2. GPU acceleration for parallel algorithms
3. Traits for zero-cost abstraction
4. Inline small functions
5. Avoid allocations in hot loops

Troubleshooting

Missing Dependencies

# Reinstall environment
pixi install --force

# Update Pixi
pixi self-update

GPU Not Working

# Check for GPU support
mojo -c "from sys import has_accelerator; print(has_accelerator())"

# May need appropriate NVIDIA/AMD drivers

Python Interop Issues

# Ensure Python 3.11+
python3 --version

# Rebuild module
cd python-interop
pixi run build

Contributing

When adding new samples:

1. Create directory under samples/
2. Add mojoproject.toml or reference parent
3. Include README.md with description
4. Add test file (test_*.mojo)
5. Update this file

Resources

• Official Docs: See /mojo/ root README
• Compiler Guide: See compiler/CLAUDE.md
• Language Features: See compiler/examples/

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Last Updated: January 23, 2026 Status: All examples tested and working