Osprey Programming Language

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

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Installation

# macOS / Linux (Homebrew)
brew install nimblesite/tap/osprey

# Windows (Scoop)
scoop bucket add nimblesite https://github.com/Nimblesite/scoop-bucket
scoop install osprey

Osprey shells out to LLVM (llc) and a C compiler at compile time; the package managers pull those in as dependencies (llvm for brew; llvm + gcc for scoop).

The VS Code extension (nimblesite.osprey) bundles a version-matched compiler for syntax checking.

Language Features

• 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

Revolutionary Safety

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

Syntax Example

// 🔒 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))
} 

Project Structure

• crates/ - Main Osprey compiler (Rust workspace: osprey-ast, osprey-syntax, osprey-types, osprey-codegen, osprey-runtime-sys, osprey-cli)
• tree-sitter-osprey/ - Tree-sitter grammar (parser)
• compiler/ - Pure-C runtime sources (runtime/) + example programs (examples/)
• vscode-extension/ - VSCode language support
• website/ - Documentation site
• webcompiler/ - Browser-based compiler
• homebrew-package/ - Homebrew tap
• .devcontainer - Configuration for the dev container

Documentation

• Language specification
• API reference
• Contributing guide
• Release process — tag v* to release; CI runs only on PRs to main.

Development

Built on proven tech: Rust for the compiler, tree-sitter 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".

make build         # C runtime archives + cargo build --release + extension
make test          # Run all tests + coverage thresholds
make lint          # cargo clippy + extension lint
make ci            # lint + test + build (full CI simulation)
make install       # Install compiler + runtime archives locally

The compiler binary lands at target/release/osprey.

Status

🚧 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 docs/specs/ for implementation status.

Recent Major Updates

• 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!)

License

MIT License - see LICENSE

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