ema

ema is a WIP next-gen Haskell static site generator that is change-aware. In addition to static site generation, it provides a live server that hot-reload's on code or data change¹.

The ultimate goal of ema is to make it possible to easily implement your own neuron, or just about any app that creates a browser view of arbitrarily changing data (on disk, database, or whatever). ema is designed to facilitate creation of apps whose data is normally edited via traditional mechanisms (eg: text editor) but rendered as a delightful web page - so as to provide an economical read-only view, of your data, on desktop & mobile.

The simplest ema app looks like this:

main :: IO ()
main = do
  let name :: Text = "Srid"
  runEmaPure $ \() ->
    encodeUtf8 $ "<b>Hello,</b> " <> name

Hacking

Run bin/run (or Ctrl+Shift+B in VSCode). This runs the clock example; modify ./.ghcid to run a different example.

TODO

• MVP
• Implement hot reload, and ditch browser-sync
  • server to client refresh
  • client to server reconnect (on ghcid reload, or accidental client disconnect)
    • or, investigate https://hackage.haskell.org/package/ghci-websockets
• Multi-websocket-client support
• Refactor Server.hs & Changing.hs

pre-announce,

• plan features, re: hakyll
• CLI UX (opts, logging, etc.)
• add common examples,
  • filesystem watcher
  • docs site (w/ sidebar and possibly even search)
• documentation (howto)

doc notes,

• use async:race to avoid ghcid ghosts
• at most one ws client supported right now
• tailwind + blaze-html layout (BlazeWind?) for no-frills getting started

---

1. At the moment, only data change triggers a true hot reload; but code change triggers reload via a full page refresh in the browser, which creates a subtle flicker. Ideally this should be improved somehow, possibly by persisting the server and websocket across ghci(d) restarts (cf. ghci-websockets). ↩︎