App.re

[%bs.raw {|require('./App.css')|}];

[@bs.module] external logo : string = "./logo.svg";

type action = Hello | Goodbye | Whatever;

type state = {
  greeting: string
};

let component = ReasonReact.reducerComponent("App");

let make = (~message, _children) => {
  ...component,
  initialState: () => { greeting: "hi" },
  reducer: (action, _state: state) =>
    switch (action) {
    | Hello => ReasonReact.Update({..._state, greeting: "hello" })
    | Goodbye => ReasonReact.Update({..._state, greeting: "goodbye" })
    | Whatever => ReasonReact.Update({..._state, greeting: "whatever" })
    },
  didMount: self => {
    let watcherID = ReasonReact.Router.watchUrl(url => {
      Js.log(url.path)
      switch (url.path) {
      | ["hello"] => self.send(Hello)
      | ["goodbye"] => self.send(Goodbye)
      | ["whatever"] => self.send(Whatever)
      | _ => self.send(Hello)
      }
    });
    self.onUnmount(() => ReasonReact.Router.unwatchUrl(watcherID));
  },
  render: _self =>
    <div className="App">
      <div className="App-header">
        <img src=logo className="App-logo" alt="logo" />
        <h2> (ReasonReact.string(message)) </h2>
      </div>
      <p className="App-intro">
        (ReasonReact.string("To get started, edit"))
        (ReasonReact.string(_self.state.greeting))
        <code> (ReasonReact.string(" src/App.re ")) </code>
        (ReasonReact.string("and save to reload."))
      </p>
    </div>
};

whatever.re

/* self.send is not called when visiting /hello or /goodbye */
let watcherID = ReasonReact.Router.watchUrl(url => {
  switch (url.path) {
  | ["hello"] => self.send(Hello)
  | ["goodbye"] => self.send(Goodbye)
  }
});

/* self.send is called when visiting /#hello or /#goodbye */
let watcherID = ReasonReact.Router.watchUrl(url => {
  switch (url.hash) {
  | "hello" => self.send(Hello)
  | "goodbye" => self.send(Goodbye)
  }
});

type thing = {
  path: list(string)
};

let x = { path: ["hello", 5] };

let d = switch (x.path) {
| ["hello", _] => true
| _ => false
};

Js.log(d);

This obviously fails to compile, but let x = { path: ["hello", "world"]}; obviously does not.