IMPORTANT: Execution order on these steps is VITAL

$ npm install
$ esy
$ npm run hackify ./_build/default/src/path_to_file.bs.js

trite@DESKTOP-0ACBTNR:~/git/hackerrank-melange$ npm install

added 125 packages, and audited 126 packages in 1s

17 packages are looking for funding
  run `npm fund` for details

1 high severity vulnerability

To address all issues, run:
  npm audit fix

Run `npm audit` for details.
trite@DESKTOP-0ACBTNR:~/git/hackerrank-melange$ esy
info esy 0.6.12-dev (using esy.json)
trite@DESKTOP-0ACBTNR:~/git/hackerrank-melange$ npm run hackify ./_build/default/src/AVeryBigSum.bs.js 

> hackerrank-melange-webpack-only-part@0.1.0 hackify
> webpack build -t "node" --mode production --entry  "./_build/default/src/AVeryBigSum.bs.js"

asset main.js 9.68 KiB [compared for emit] [minimized] (name: main)
orphan modules 159 KiB [orphan] 29 modules
./_build/default/src/AVeryBigSum.bs.js + 22 modules 121 KiB [not cacheable] [built] [code generated]
webpack 5.72.1 compiled successfully in 832 ms
trite@DESKTOP-0ACBTNR:~/git/hackerrank-melange$ 

melange-basic-template

A simple project template using Melange.

Getting started

You will need esy package manager to obtain OCaml and Melange sources. See esy installation instructions here.

Once esy is available, run

esy

to install all dependencies.

Then:

esy build

to build the project. This command, as constructed in esy.json,

1. generates a symbolically linked dir bs-platform in node_modules, which is helpful when using JavaScript bundlers like Webpack that expect to find Melange stdlib JavaScript files under node_modules/bs-platform.
2. builds the project.

Now you should see a _build folder with all generated files, you can run

esy x node _build/default/src/Main.bs.js

to see the result of the script running.