TypeError: Express is not a function

1

I am trying to write a Express server in typescript (basically following the last chapter of the book “introducing rescript”)

I wrote this code

open Express
let app = express()
app -> use(jsonMiddleware())
app -> get("/", (_, response) => {
open NodeJs
response->sendFile(Path.join([Global.dirname, "index.html"]))->ignore
})

let _ = app->listen(4000, _=> {
Js.Console.log("server is running on 4000")})

my bsconfig.json looks like

{
  "name": "example1",
  "version": "0.1.0",
  "sources": {
    "dir" : "src",
    "subdirs" : true
  },
  "package-specs": {
    "module": "es6",
    "in-source": true
  },
  "suffix": ".bs.js",
  "jsx": { "version": 4, "mode": "classic" },
  "bs-dependencies": [
    "@rescript/react", 
    "rescript-express", 
    "rescript-webapi", 
    "rescript-nodejs"],
  "reason": {"react-jsx": 3}  
}

and package.json like

{
  "name": "example1",
  "version": "0.1.0",
  "type": "module",
  "scripts": {
    "clean": "rescript clean -with-deps",
    "build": "rescript build && webpack",
    "watch": "rescript build -w"
  },
  "keywords": [
    "ReScript"
  ],
  "author": "",
  "license": "MIT",
  "devDependencies": {
    "copy-webpack-plugin": "^11.0.0",
    "css-loader": "^6.7.3",
    "html-webpack-plugin": "^5.5.0",
    "rescript": "^10.0.1",
    "style-loader": "^3.3.1",
    "webpack": "^5.75.0",
    "webpack-cli": "^5.0.1",
    "webpack-html-plugin": "^0.1.1"
  },
  "dependencies": {
    "@rescript/react": "^0.11.0",
    "rescript-express": "^0.4.1",
    "rescript-nodejs": "^14.3.1",
    "rescript-webapi": "^0.7.0"
  }
}

when I say node src/Server.bs.js I get error

╰─$ node src/Server.bs.js
file:///Users/foo/code/Rescript/example1/src/Server.bs.js:6
var app = Express();
^

TypeError: Express is not a function
at file:///Users/foo/code/Rescript/example1/src/Server.bs.js:6:11
at ModuleJob.run (node:internal/modules/esm/module_job:193:25)

Node.js v19.6.1

2

Add express to your dependencies