Getting Started

Prerequisites

• LLVM 18+ with clang, opt, and lld
• GCC (for runtime compilation)
• Git

On Ubuntu/Debian:

sudo apt install llvm-18 clang-18 lld-18 gcc git

On Arch Linux:

sudo pacman -S llvm clang lld gcc git

On macOS:

brew install llvm gcc git

Build from Source

git clone https://github.com/codeyousef/SeenLang.git
cd SeenLang
./scripts/safe_rebuild.sh

The production compiler lands at compiler_seen/target/seen.

Install

Copy the binary to your PATH:

sudo cp compiler_seen/target/seen /usr/local/bin/seen

Or add the project directory:

export PATH="$PATH:/path/to/SeenLang/compiler_seen/target"

Hello World

Create hello.seen:

fun main() {
    println("Hello, Seen!")
}

Compile and run:

seen build hello.seen -o hello
./hello

Or use JIT execution (no binary produced):

seen run hello.seen

Your First Project

Project Structure

A Seen project uses Seen.toml for configuration:

my_project/
├── Seen.toml
├── src/
│   └── main.seen
└── tests/
    └── test_main.seen

Seen.toml

[project]
name = "my_project"
version = "0.1.0"
language = "en"

[registries]
default = "https://seen.yousef.codes/packages"

[dependencies]
mathx = "0.1.0"

[native.dependencies]

The language field sets the keyword language. Options: en, ar, es, ru, zh, fr.

A Bigger Example

class Counter {
    var count: Int

    static fun new() r: Counter {
        return Counter { count: 0 }
    }

    fun increment() {
        this.count = this.count + 1
    }

    fun value() r: Int {
        return this.count
    }
}

fun main() {
    let counter = Counter.new()
    var i = 0
    while i < 10 {
        counter.increment()
        i = i + 1
    }
    println("Count: {counter.value()}")
}

Compile:

seen build src/main.seen -o my_project
./my_project

Editor Setup

VS Code (Recommended)

cd vscode-seen
npm install
npm run package
code --install-extension seen-*.vsix

The extension provides:

• Syntax highlighting
• IntelliSense via built-in LSP
• Real-time error diagnostics
• Code formatting
• 34 code snippets

Any Editor (LSP)

Seen includes a built-in language server:

seen lsp

Neovim:

require'lspconfig'.seen.setup{
  cmd = {"seen", "lsp"},
  filetypes = {"seen"},
  root_dir = require'lspconfig.util'.root_pattern("Seen.toml", ".git"),
}

Emacs:

(lsp-register-client
 (make-lsp-client :new-connection (lsp-stdio-connection '("seen" "lsp"))
                  :major-modes '(seen-mode)
                  :server-id 'seen-lsp))

Writing in Other Languages

The same hello world in Arabic:

دالة main() {
    println("!مرحبا، سين")
}

Compile with language flag:

seen build hello_ar.seen -o hello --language ar

See Multi-Language Support for full translation tables.

Next Steps

• Language Guide -- complete syntax reference
• CLI Reference -- all compiler commands and flags
• API Reference -- standard library documentation