Exclude<any,whatever> (another way of negated type #29317)

[escKeyStroke]

Hi

Search Terms

Exclude<any
type subtraction
any but
all types except
Checked: #31579 #29317

Suggestion

type T00 = Exclude<any,whatever>

T00 should be composed of any (all) types, except those types that are assignable to whatever

Use Cases

I definded a bunch of functions according to the following interface:

interface ecafretni { (x:any, y:Q): any }

x literally takes any type, there's no possible narrowing down. Think of a general-purpose deep-copy function, for example. Q is some other interface I defined somewhere. Here's the use case: I had to change the order of the arguments of ecafretni to (y:Q, x:any) and I was wishing that TypeScript would point out all the (hundreds of) points where I was calling functions abiding by that interface, so that I woulnd't miss any. But it wouldn't because, of course, type Q is assignable to any and type any is assignable to Q.

So I came up with another type to use in the place of any: R = Exclude<any,Q>, and redefine ecafretni argument types as f(y:Q, x:R). But it's not working. It seems that R behaves the same way as any.

Examples

const f = function( x : Exclude<any,Number> ){};
const x:Number = 4;
const v = f(x); // TYPE MISMATCH !!!! (not caught by TypeScript)

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

[MartinJohns]

Duplicate of #29317.

[jack-williams]

Duplicate of #29188

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.