Awesome
React-Haskell ![Hackage](https://img.shields.io/hackage/v/react-haskell.svg?style=flat-square)
As crazy as it seems, using React and Haskell together just may be a good idea.
I was driven to create this thing because I had a large existing Haskell codebase I wanted to put online. However, even without existing code, I think a lot of problems are better modeled in Haskell than JavaScript or other languages. Or you might want to use some existing Haskell libraries.
Examples
Let's put a simple paragraph on the page:
sample :: ReactNode a
sample = p_ [ class_ "style" ] $ em_ "Andy Warhol"
main :: IO ()
main = do
Just doc <- currentDocument
let elemId :: JSString
elemId = "inject"
Just elem <- documentGetElementById doc elemId
render sample elem
That creates a DOM node on the page that looks like:
<p class="style">
<em>Andy Warhol</em>
</p>
We can make that a little more complicated with some more child nodes.
sample :: ReactNode a
sample = div_ [ class_ "beautify" ] $ do
"The Velvet Underground"
input_
"Lou Reed"
But of course that input doesn't do anything. Let's change that.
sample :: JSString -> ReactNode JSString
sample = div_ $ do
"Favorite artist:"
input_ [ onChange (Just . value . target) ]
text str
Getting Started
The first step is a working GHCJS installation. The easiest way is to download a virtual machine with GHCJS pre-installed. I recommend <a href="https://github.com/joelburget/ghcjs-box">ghcjs-box</a>.
Now that GHCJS is installed we can use cabal to create a project.
$ mkdir project
$ cd project
$ cabal init # generate a .cabal file
Now edit the cabal file to include dependencies.
build-depends:
base >= 4.8 && < 5,
ghcjs-base,
ghcjs-dom,
react-haskell >= 1.3
Now we can write Main.hs
.
sample :: ReactNode a
sample = p_ [ class_ "style" ] $ em_ "Andy Warhol"
main :: IO ()
main = do
Just elem <- elemById "id"
render sample elem
Next Steps
Reference
Additional Resources
Is it Right for Me?
React-Haskell is a great tool for building web UI from Haskell. However, you may want to consider the alternatives:
- By writing plain React / JSX you can speed development by avoiding the GHCJS compilation step. This also has the advantage of being a bit more universal - more people use React through JSX than React-Haskell.
- ghcjs-react is a very similar project.
- Reflex is an FRP system built with GHCJS in mind.