Seen Language Documentation

Seen is a self-hosted systems programming language with multi-language keywords, region-based memory management, and LLVM-powered compilation.

fun main() {
    let names = ["Alice", "Bob", "Charlie"]
    for name in names {
        println("Hello, {name}!")
    }
}

Key Features

• Self-hosted compiler -- 62,000+ lines of Seen compiling itself
• Multi-language keywords -- write code in English, Arabic, Spanish, Russian, Chinese, or French
• LLVM backend -- ThinLTO, vectorization, aggressive inlining (1.0x--1.5x Rust performance)
• Region-based memory -- no garbage collector
• Fast compilation -- fork-parallel IR generation with content-addressed incremental caching
• GPU compute -- @compute shaders via Vulkan/GLSL pipeline
• SIMD intrinsics -- f32x4, i32x4, f64x2, etc.
• Async/await -- LLVM coroutine-based concurrency

Documentation

Getting Started

• Getting Started -- installation, first program, project setup
• Language Guide -- complete syntax and semantics reference
• CLI Reference -- every command and flag

Core Concepts

• Memory Model -- regions, ownership, borrowing, defer
• Concurrency -- async/await, parallel_for, sync primitives
• Metaprogramming -- comptime, decorators, derive macros, reflection

Specialized Topics

• SIMD and GPU -- vector types and GPU compute shaders
• Multi-Language Support -- keyword translations and adding languages
• FFI -- C interop, extern functions, linking
• Tooling -- VS Code extension, LSP, formatting, debugging

Project & Build

• Project Configuration -- Seen.toml format and project structure
• Packaging -- static registry layout, publishing, and hosting
• Compiler Architecture -- 5-stage pipeline internals
• Bootstrap System -- self-hosting verification and safe rebuilds
• Known Limitations -- current bugs and workarounds

API Reference

• API Reference Index -- standard library and runtime overview
• Core Types -- Option, Result, Unit, Ordering
• Strings -- String, StringBuilder
• Collections -- Array, Vec, HashMap, BTreeMap, etc.
• Math -- math functions and constants
• I/O -- File, stdin/stdout, reading and writing
• Process -- Command execution, environment
• Synchronization -- Mutex, RwLock, Channel, AtomicInt
• Random -- random number generators
• Bitfield -- bit manipulation types
• Binary -- serialization and compression
• JSON -- JSON derive and parsing
• Reflection -- runtime type information
• GPU -- GPU types and runtime functions