NonReducibleUnknown type

Signature:

export type NonReducibleUnknown = {} | null | undefined;

Remarks

T | unknown reduces to unknown and that can be problematic when it comes to contextual typing. It especially is a problem when the union has a function member, like here:

declare function test(cbOrVal: ((arg: number) => unknown) | unknown): void;
test((arg) => {}) // oops, implicit any

This type can be used to avoid this problem. This union represents the same value space as unknown.