Retained Props

Copy a few props into a special field to emulate ReactJS' lifecycle events' prevProps/nextProps functionality.

type retainedProps = {message: string};
let component = ReasonReact.statelessComponentWithRetainedProps "RetainedPropsExample";
let make ::message _children => {
  ...component,
  retainedProps: {message: message},
  didUpdate: fun {oldSelf, newSelf} =>
    if (oldSelf.retainedProps.message !== newSelf.retainedProps.message) {
      /* do whatever sneaky imperative things here */
      Js.log "props `message` changed!"
    },
  render: fun _self => <div> (ReasonReact.stringToElement message) </div>
};