compare and equal

[cknitt]

Add compare and equal functions, see #77.

Modules:

• Array
• Int
• Float
• String
• Date
• Null
• Nullable

TODO:

• Docs
• Tests

[jmagaram]

I put some comments in the issue. I think we should discuss there, not here. I see problems using compare with options when sorting arrays - data first is awkward. Same with instantiating a Belt.Set or Map. I'm not sure where data first really works for option since you're going to end up with a number like -1, 0, or 1 and then what to do with it? Also does the subtraction implementation for int.compare work with NaN and other weird cases; it might.

let compareInt = (x, y) => x < y ? -1 : x > y ? 1 : 0
let x = [Some(1), None, Some(5), Some(2)]->Array.sortInPlace((a, b) => Option.cmp(a, b, compareInt))

[jmagaram]

The implementation fails with overflow like Int.Constants.minValue - Int.Constants.maxValue .

[jmagaram]

Might want to explain in the docs which equality operator is used for floats/ints. if you use === then NaN != NaN and -0.0==+0.0 which seems fine to me. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/is

[jmagaram]

I'm confused about the string compare flavors. How does the version you've coded relate to String.localeCompare with or without options? Is there any advantage to it? The docs should explain when to use which ones. I'm wondering if these compare options should be grouped/unified together so the developer can easily see their choices together. Maybe String.compareLocale, String.compareLocaleWith, and String.compare, where the last is the version you've coded and the first two are the String.localeCompare versions with and without options.

https://262.ecma-international.org/7.0/#sec-abstract-relational-comparison