rescript-compiler VS melange

Probably every developer that comes to ReScript stumbles upon a dilemma about which module from the standard library they should use to work with JavaScript API.

I wasn't familiar with this before. Thanks for being it to my attention! https://rescript-lang.org/

I find ReScript (https://rescript-lang.org/) fundamentally better than TypeScript. It has easy FFI and a sound typesystem. With Rescript you wont have any runtime errors, like you can with typescript. But compared to vanilla javascript typescript is a big improvement.

Overall, both TypeScript and ReScript have several advantages over JavaScript, and which one you choose will depend on your specific needs and preferences. TypeScript is a good choice if you want to take advantage of static typing and strong integration with popular front-end frameworks, while ReScript is a good choice if you want a simple and easy-to-learn language with a focus on readability and performance. Regardless of which language you choose, all three are powerful tools that can help you build high-quality web applications.

I’ve recently been ripped from doing Functional Programming in Elm on the front-end and ReScript on the back-end in a Serverless Environment into Object Oriented Programming using Angular & TypeScript on the front-end and TypeScript on the back-end in a server full environment. It’s been quite a shock to go back to what I moved on from 7 years ago. Thankfully TypeScript has started to incorporate some Functional Programming constructs so I can keep my sanity (or at least try).

This year, I chose Roc. It’s a strictly typed functional language. As someone who loves Elm, a strictly typed functional language for front-end web development, I was lacking a language for everything else (server, cli, etc). ReScript has been my stand in for various reasons. I was excited to try Roc lang for last year’s Advent of Code, but my youngest daughter convinced me to use Lua for Roblox. I figured after a whole year, things would be much more stable now.

Because you use rescript

The correct answer is actually rescript

ReScript compilation speeds are really fast out of the box. But, sometimes editing certain files can take longer to compile than you'd expect it to.

So it's Reason, not ReasonML which the umbrella project's name, and Rescript is a imcompatible syntax split from the Bucklescript team (that previously transpiled Reason to JS). Bucklescript's new name is... Rescript.

But not everyone agrees with the split and work is being done on Melange to replace Bucklescript : https://github.com/melange-re/melange

Ultimately JsOfOcaml can directly transpile Ocaml to JS.

In reality, most folks that developed BuckleScript frontends with ReasonML switched to ReScript syntax and are happy with it. Some felt more friction because of their reliance on PPXes or FP-heavy libraries (like Relude) and those people tend to use the Melange fork of BuckleScript or they switched to js_of_ocaml.

There is a fork of ReScript that supports ReasonML syntax and with the goal of maintaining Ocaml compatibility: https://github.com/melange-re/melange.

For OCaml and ReasonML your options are js_of_ocaml (mentioned here in ReasonML docs) or a fairly new fork of BuckleScript called melange. They differ in implementation and output, with JSOO taking intermediate bytecode generated by ocamlc and turning it into unreadable JS, vs Melange being a patched compiler that builds more human-readable JS.

TL;DR: Reason is, and always has been, independent of ReScript (formerly BuckleScript) and is still actively maintained. If you want to use Reason or OCaml to make native code you can. If you want to compile JS from OCaml or Reason you also still can, but you'll want to use either js_of_ocaml or a BuckleScript fork named Melange that was made in response to the BuckleScript/ReScript people's shenanigans. And if you only care about JS-like syntax and JS output, you can use ReScript.

While banging my head against the wall trying to understand the Dune build system used with OCaml and the Melange project I came across these great simple videos by @TheEduardoRFS.