A modern functional programming language designed for elegance, safety, and performance. Written in Go, outputs to LLVM.

⭐ Star us on GitHub to support the project and allow us to submit to Homebrew! ⭐

# Add the tap
brew tap melbournedeveloper/osprey

# Install Osprey
brew install osprey

• Functional-first: Immutable data, pattern matching, pipe operators
• Algebraic Effects: First-class effects system with compile-time safety
• Type-safe: Algebraic data types with variant types
• HTTP-native: Built-in server/client with streaming support
• Fiber concurrency: Lightweight isolated execution contexts
• Zero-cost abstractions: Compiles to efficient LLVM IR

🚀 World's first language with 100% compile-time effect safety - unhandled effects cause compilation errors, not runtime crashes!

// 🔒 HANDLER ISOLATION SIMPLE TEST 🔒

effect Logger {
    log: fn(string) -> Unit
}

// Main function with different handlers
fn main() -> Unit = {
    print("🔒 Testing Handler Isolation")
    
    // Production handler
    let result1 = handle Logger
        log msg => print("[PROD] " + msg)
    in {
        perform Logger.log("Processing task: 5")
        10
    }
    
    // Debug handler
    let result2 = handle Logger
        log msg => print("[TEST] " + msg)
    in {
        perform Logger.log("Processing task: 12")
        24
    }
    
    // Silent handler
    let result3 = handle Logger
        log msg => 0
    in {
        perform Logger.log("Processing task: 0")
        0
    }
    
    print("📊 Results: Prod=" + toString(result1) + ", Test=" + toString(result2) + ", Silent=" + toString(result3))
} 

• compiler/ - Main Osprey compiler (Go + ANTLR)
• vscode-extension/ - VSCode language support
• website/ - Documentation site
• webcompiler/ - Browser-based compiler
• homebrew-package/ - Homebrew tap
• .devcontainer - Configuration for the dev container

• Language specification
• API reference
• Contributing guide

Built on proven tech: Go for the compiler, ANTLR for parsing, and LLVM for code generation.

AI-Assisted Development: Claude Sonnet 4 with Cursor makes implementing language features accessible. Check out CONTRIBUTING.md for the workflow.

Use VS Code Dev Containers - strongly recommended. Open in VS Code and hit "Reopen in Container".

cd compiler
make build         # Build compiler
make test          # Run tests
make install       # Install locally

🚧 Alpha: Core language features implemented. Algebraic effects system working with compile-time safety, but are missing some features. HTTP and advanced features in development.

See compiler/spec/ for implementation status.

• Algebraic Effects System: Complete implementation with compile-time safety guarantees
• Effect Declarations: effect keyword for defining effect operations
• Perform Expressions: perform keyword for effect operations
• Handler Expressions: handle...in syntax for effect handling
• Compile-Time Verification: Unhandled effects cause compilation errors (world-first!)

MIT License - see LICENSE

⭐ Give us a star on GitHub if you like what we're building! ⭐