TinyWL Haskell Implementation

Project Overview

This project aims to create a total Haskell implementation of TinyWL (Tiny Wayland Compositor) using Haskell bindings for wlroots. The ultimate goal is to provide a way to test and validate Haskell bindings for the wlroots library.

Current Status

Please check TODO.md

The project is currently in Stage 1 of development. I am working on refactoring TinyWL's main function into Haskell.

Stage 1 Goal

Create a Haskell implementation of c_main that uses Haskell bindings and implements its logic in Haskell.

System Architecture

Component Overview

The following diagram shows the main components of our Wayland compositor and how they relate to each other:

graph TB
    subgraph "Haskell Layer"
        A[Haskell Main]
        B[TinyWL.FFI]
    end

    subgraph "Bindings Layer"
        C[wlhs - Wayland Haskell Bindings]
    end

    subgraph "C Layer"
        D[TinyWL C Server]
    end

    subgraph "System Layer"
        E[wlroots]
        F[Wayland Protocol]
        G[Linux Kernel / Display Server]
    end

    A -->|uses| B
    A -->|uses| C
    B -->|FFI calls| D
    C -->|binds to| E
    D -->|uses| E
    E -->|implements| F
    F -->|interacts with| G

    classDef haskell fill:#f9f,stroke:#333,stroke-width:2px;
    classDef c fill:#9cf,stroke:#333,stroke-width:2px;
    classDef system fill:#fcf,stroke:#333,stroke-width:2px;
    class A,B haskell;
    class C,D c;
    class E,F,G system;

Operational Flow

This sequence diagram illustrates how these components interact during the lifecycle of the compositor:

sequenceDiagram
    participant Haskell as Haskell Main
    participant WLHS as wlhs (Wayland Haskell bindings)
    participant FFI as FFI Layer
    participant C as C TinyWL Server
    participant WLR as wlroots
    participant System as System/OS

    Haskell->>WLHS: Use Wayland Haskell bindings
    WLHS->>WLR: Initialize logging (wlr_log_init)
    Haskell->>FFI: Call c_server_create
    FFI->>C: server_create()
    C-->>FFI: Return server pointer
    FFI-->>Haskell: Return server pointer

    Haskell->>FFI: Call c_server_init
    FFI->>C: server_init()
    C->>WLR: Initialize wlroots
    WLR->>System: Set up Wayland display
    System-->>WLR: Return display info
    WLR-->>C: Return init status
    C-->>FFI: Return init success status
    FFI-->>Haskell: Return init success status

    Haskell->>FFI: Call c_server_start
    FFI->>C: server_start()
    C->>System: Create Wayland socket
    System-->>C: Return socket name
    C-->>FFI: Return socket name
    FFI-->>Haskell: Return socket name

    Haskell->>System: Set WAYLAND_DISPLAY environment variable

    alt Startup command provided
        Haskell->>FFI: Call c_server_set_startup_command
        FFI->>C: server_set_startup_command()
        C->>System: Store startup command
    end

    Haskell->>FFI: Call c_server_run
    FFI->>C: server_run()
    C->>WLR: Start Wayland event loop
    WLR->>System: Handle input/output events

    Note over System: Wayland compositor running

    Haskell->>WLHS: Log messages via wlr_log
    WLHS->>WLR: Pass log messages

    Haskell->>FFI: Call c_server_destroy
    FFI->>C: server_destroy()
    C->>WLR: Cleanup wlroots resources
    C->>System: Close Wayland socket

Getting Started

Ensure you have the submodules cloned down
I created a shell.nix, you should be able to simply run nix-shell
then cabal run
tinywl will create a window you can play around with.
- alt left click to move the window around and alt right click to resize it.

Note

I ran created and tested this on a Debian laptop with xmonad, please let me know if you run into issues on other configurations

Contributing

We welcome contributions to this project. This project is in its infancy however you can find an aspirational contrib guide here CONTRIBUTING.md. At this early stage contributing won't be as strict as outlined; the only requirement will be a PR that moves towards the stated goals.

License

LICENSE

Contact

The best way to reach me is with an email to shane@peregrinum.dev

l-Shane-l / tiny-wlhs

readme