Should unions and non-primitives be allowed for relational comparisons?

[DanielRosenwasser]

To quote 4.19.1 of the spec:

4.19.3 The <, >, <=, >=, ==, !=, ===, and !== operators

These operators require one or both of the operand types to be assignable to the other. The result is always of the Boolean primitive type.

	Any	Boolean	Number	String	Other
Any	Boolean	Boolean	Boolean	Boolean	Boolean
Boolean	Boolean	Boolean
Number	Boolean		Boolean
String	Boolean			Boolean
Other	Boolean				Boolean

This has probably unintended consequences in the case of union types:

var x: string | number = "hello";
var y: number = 10;
var z: string | number = -1;

if (x < y && x <= z) {
}

The question is: is this still desirable behavior?

Anders Hejlsberg (@ahejlsberg) Ryan Cavanaugh (@RyanCavanaugh) Dan Quirk (@danquirk) Mohamed Hegazy (@mhegazy) Jason Freeman (@JsonFreeman)

[LPGhatguy]

Comparing strings and numbers is perfectly valid (if not a little wacky) JavaScript, isn't it?

[weswigham]

I mean, comparing anything is "valid javascript" (objects, arrays...), if not obviously meaningful.

[DanielRosenwasser]

From an offline discussion, the consensus seems to be that the equality operations could keep something like this behavior, whereas other comparison operators should have their own rules.

[mhegazy]

We should keep the idea of a new relationship on the backlog, i do not think we solved the underlying issue. closing this to avoid duplication though.

[DanielRosenwasser]

This wasn't regarding the comparable relation, and even if it was, we've decided to use it for nullable types.