IsBivariant
Type description + examples
Most of the time when I want to test for equality, I actually care about mutual assignability (aka bivariance), not exact equality.
import {IsEqual, And} from 'type-fest'
type IsBivariant<T1, T2> = And<T1 extends T2 ? true : false, T2 extends T1 ? true : false>;
type T1 = { k: string }
type T2 = { k: string }
type T3 = T1 | T2
type test1 = IsEqual<T1, T3>; // false
type test2 = IsBivariant<T1, T3>; // trueType source
No response
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sindresorhus / type-fest
A collection of essential TypeScript types
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