Typeservicesv0.6.0

ExcludeExactly

A stricter version of Exclude<T, U>Exclude<T, U> that excludes types only when they are exactly identical.

type ExcludeExactly<Union, Delete> = IfNotAnyOrNever<Union, _ExcludeExactly<Union, Delete>, // If `Union` is `any`, then if `Delete` is `any`, return `never`, else return `Union`. If<IsAny<Delete>, never, Union>, // If `Union` is `never`, then if `Delete` is `never`, return `never`, else return `Union`. If<IsNever<Delete>, never, Union>>

type ExcludeExactly<Union, Delete> = IfNotAnyOrNever<Union, _ExcludeExactly<Union, Delete>, // If `Union` is `any`, then if `Delete` is `any`, return `never`, else return `Union`. If<IsAny<Delete>, never, Union>, // If `Union` is `never`, then if `Delete` is `never`, return `never`, else return `Union`. If<IsNever<Delete>, never, Union>>

import type {ExcludeExactly} from 'type-fest';

type TestExclude1 = Exclude<'a' | 'b' | 'c' | 1 | 2 | 3, string>;
//=> 1 | 2 | 3

type TestExcludeExactly1 = ExcludeExactly<'a' | 'b' | 'c' | 1 | 2 | 3, string>;
//=> 'a' | 'b' | 'c' | 1 | 2 | 3

type TestExclude2 = Exclude<'a' | 'b' | 'c' | 1 | 2 | 3, any>;
//=> never

type TestExcludeExactly2 = ExcludeExactly<'a' | 'b' | 'c' | 1 | 2 | 3, any>;
//=> 'a' | 'b' | 'c' | 1 | 2 | 3

type TestExclude3 = Exclude<{a: string} | {a: string; b: string}, {a: string}>;
//=> never

type TestExcludeExactly3 = ExcludeExactly<{a: string} | {a: string; b: string}, {a: string}>;
//=> {a: string; b: string}

 Improved Built-in

import type {ExcludeExactly} from 'type-fest';

type TestExclude1 = Exclude<'a' | 'b' | 'c' | 1 | 2 | 3, string>;
//=> 1 | 2 | 3

type TestExcludeExactly1 = ExcludeExactly<'a' | 'b' | 'c' | 1 | 2 | 3, string>;
//=> 'a' | 'b' | 'c' | 1 | 2 | 3

type TestExclude2 = Exclude<'a' | 'b' | 'c' | 1 | 2 | 3, any>;
//=> never

type TestExcludeExactly2 = ExcludeExactly<'a' | 'b' | 'c' | 1 | 2 | 3, any>;
//=> 'a' | 'b' | 'c' | 1 | 2 | 3

type TestExclude3 = Exclude<{a: string} | {a: string; b: string}, {a: string}>;
//=> never

type TestExcludeExactly3 = ExcludeExactly<{a: string} | {a: string; b: string}, {a: string}>;
//=> {a: string; b: string}

 Improved Built-in

Union

Union

Union

Delete

Delete

Delete

type ExcludeExactly<Union, Delete> = IfNotAnyOrNever<Union, _ExcludeExactly<Union, Delete>, // If `Union` is `any`, then if `Delete` is `any`, return `never`, else return `Union`. If<IsAny<Delete>, never, Union>, // If `Union` is `never`, then if `Delete` is `never`, return `never`, else return `Union`. If<IsNever<Delete>, never, Union>>

import type {ExcludeExactly} from 'type-fest'; type TestExclude1 = Exclude<'a' | 'b' | 'c' | 1 | 2 | 3, string>; //=> 1 | 2 | 3 type TestExcludeExactly1 = ExcludeExactly<'a' | 'b' | 'c' | 1 | 2 | 3, string>; //=> 'a' | 'b' | 'c' | 1 | 2 | 3 type TestExclude2 = Exclude<'a' | 'b' | 'c' | 1 | 2 | 3, any>; //=> never type TestExcludeExactly2 = ExcludeExactly<'a' | 'b' | 'c' | 1 | 2 | 3, any>; //=> 'a' | 'b' | 'c' | 1 | 2 | 3 type TestExclude3 = Exclude<{a: string} | {a: string; b: string}, {a: string}>; //=> never type TestExcludeExactly3 = ExcludeExactly<{a: string} | {a: string; b: string}, {a: string}>; //=> {a: string; b: string} Improved Built-in