Type Alias DrainOuterGeneric<T>

Utility to reduce depth of TypeScript's internal type instantiation stack.

Example:

type A<T> = { item: T }

type Test<T> = A<
  A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<T>>>>>>>>>>>>>>>>>>>>>>>>
>

// type Error = Test<number> // Type instantiation is excessively deep and possibly infinite.ts (2589)
Copy

To fix this, we can use DrainOuterGeneric:

type A<T> = DrainOuterGeneric<{ item: T }>

type Test<T> = A<
 A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<A<T>>>>>>>>>>>>>>>>>>>>>>>>
>

type Ok = Test<number> // Ok
Copy