PureScript on Android

I’ve been playing around with PureScript on Android via React Native.

Here’s what a TodoMVC-style app looks like:

And here’s what the guts of the code look like:

render :: forall props eff. Render props AppState eff
render ctx = do
  (AppState state) <- readState ctx
  return $ 
    view [(style "container")] [
      text [style "title"] "todos",
      view [style "newTodoContainer"] [
        textInput [style "newTodo", 
                   P.value state.newTodo,
                   P.placeholder "What needs to be done?",
                   N.onChangeText \newTodo -> transformState ctx (updateNewTodo newTodo),
                   N.onSubmitEditing \_ -> transformState ctx addTodo]],
      listView [style "todoList",
                N.renderRow $ todoRow ctx,
                N.renderSeparator todoSeparator,
                N.renderHeader $ view [style "separator"] [],
                N.dataSource state.dataSource],
      view [style "bottomBar"] [
        view [style "filters"] [
           filterButton ctx state.filter All, 
           filterButton ctx state.filter Active,
           filterButton ctx state.filter Completed],
        text [style "clearCompleted", 
              N.onPress \_ -> transformState ctx clearCompleted] 
             "Clear completed"]]
        
main = do
  log "Running app"
  registerComponent "PureScriptSampleApp" component
  where
    component = createClass $ spec initialState render
    dataSource = listViewDataSource initialTodos
    initialState = updateDataSource $ AppState { nextId: 18, 
                                                 newTodo: "", 
                                                 todos: initialTodos, 
                                                 dataSource: dataSource, 
                                                 filter: All }

Check out the example source code or the React Native wrapper code.

This wrapper code builds on Phil Freeman’s purescript-react low-level wrapper for React, adding support for various elements used in Android. It is a work in progress. Functional afficionados will raise their eyebrows. Android gurus will throw their hands up in disgust. But it is PureScript. It is Android. And it is awesome.

Nicholas Kariniemi