obelisk

# Obelisk

[![Haskell Programming Language](https://img.shields.io/badge/language-Haskell-blue.svg)](http://www.haskell.org)
[![BSD3 License](http://img.shields.io/badge/license-BSD3-brightgreen.svg)](https://github.com/obsidiansystems/obelisk/blob/master/LICENSE)

<p align="center"><img src="docs/obelisk-logo-640.png" width="50%" alt="Obelisk Logo"></p>

Functional reactive web and mobile applications, with batteries included. Obelisk's goal is to represent a cohesive, highly-curated set of choices that [Obsidian Systems](https://obsidian.systems/) has made for building these types of applications in a way that is extremely fast but does not compromise on production readiness.
Supports both WASM and GHCJS frontend targets, GHC 9.14, and deploys to NixOS servers or OCI containers.

- [Overview](#overview)
  - [Who should consider using it?](#who-should-consider-using-it)
- [Quick Start](#quick-start)
- [Project Structure](#project-structure)
- [Development](#development)
  - [ob-init](#ob-init)
  - [ob-run](#ob-run)
  - [ob-repl](#ob-repl)
  - [ob-watch](#ob-watch)
  - [ob-hoogle](#ob-hoogle)
  - [ob-deploy](#ob-deploy)
- [Nix Module System](#nix-module-system)
  - [project.nix](#projectnix)
  - [Inputs](#inputs)
  - [Adding packages](#adding-packages)
  - [Package overrides](#package-overrides)
  - [Options](#options)
  - [Fine-grained builds (Experimental)](#fine-grained-builds-experimental)
- [Building](#building)
- [Deployment](#deployment)
  - [NixOS Server](#nixos-server)
  - [OCI Container](#oci-container)
  - [Native Apps](#native-apps)
- [Skeleton](#skeleton)

## Overview

Obelisk allows you to build high-quality web applications very quickly using [Reflex](https://reflex-frp.org/). In minutes you can go from an empty directory to an interactive application running in the browser, all from a single Haskell codebase! The same frontend assets can be packaged as a mobile app with [CapacitorJS](https://capacitorjs.com/) (see [Native Apps](#native-apps)). Obelisk's development environment also enables extremely rapid development and feedback. You can take advantage of Haskell's type system across the frontend and backend boundary. This means changes to your backend that would break your frontend are immediately detected during development and vice versa. Obelisk uses Haskell's compiler to give you a complete "TODO list" of what needs to be updated.

Obelisk is targeted primarily at Haskell developers who want to build high-quality web applications in Haskell, without the distractions of manually choosing and integrating technology for every piece of the system.

### Who should consider using it?

Obelisk assumes basic knowledge of [Haskell](https://www.haskell.org/) and [Reflex/Reflex-DOM](https://reflex-frp.org/), web technologies like [HTML](https://developer.mozilla.org/en-US/docs/Web/HTML) and [CSS](https://developer.mozilla.org/en-US/docs/Web/CSS), and a terminal shell like [Bash](https://en.wikipedia.org/wiki/Bash_(Unix_shell)). Knowled