Documentation could be improved around difference of == and ===

I recently came across the difference between == and ===. I probably saw it before, but it really clicked with me what the difference is.

I might be missing something, but the only hint here is that JS doesn’t have recursive compare. It doesn’t come out and say that ReScript does have recursive compare.

I tested it out with some simple code.

let a = {
  "foo": "bar",

let b = {
  "foo": "bar",

let c = a

Console.log(a === b) // false
Console.log(a === c) // true
Console.log(a == b) // true
Console.log(a == c) // true

And when you look at the compiled code you can see how it does the recursive compare:

// Generated by ReScript, PLEASE EDIT WITH CARE

import * as Caml_obj from "rescript/lib/es6/caml_obj.js";

var a = {
  foo: "bar"

var b = {
  foo: "bar"

console.log(a === b);

console.log(a === a);

console.log(Caml_obj.equal(a, b));

console.log(Caml_obj.equal(a, a));

var c = a;

export {
  a ,
  b ,
  c ,
/*  Not a pure module */

== imports a lib to do an obj compare, while === just compiles to the same in JS.

It’s a very cool language feature that saves me from having to pull in a library.

Again, I might be missing something in the docs, but this should be highlighted more as a feature.


There is an open issue in the docs repo about equality. Would be be up to tackle it? :slight_smile:

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I’ll take a look at the issue and see if I can help!

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Draft PR is here: docs: add docs for equality and comparison by jderochervlk · Pull Request #801 · rescript-association/ · GitHub

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