在联合上分配泛型类型

Question

Is there a way in TS to "distribute" a generic type over a union?

type Container<A> = { value: A };

type Containers<string | number> = Container<string> | Container<number>

(Assuming that we know from the context when to apply Containers vs Container )

Answer 1

surprisingly, type inference would do that for you:

type Container<T> = { value: T }

type Containers<T> = T extends infer A ? Container<A> : never;

the compiler is smart enough to disjoint all of them:

type C = Containers<string | number | {x: number} | {z: string} | boolean>

type C expands the following way:

type C = Container<string> | 
         Container<number> | 
         Container<false> | 
         Container<true> | 
         Container<{
           x: number;
         }> | 
         Container<{
           z: string;
         }>

ts-playground

Answer 2

Given your sample code I think you want to define a generic type that is constrained to a union of types. One of these should fit your bill.

type Container<T> = { value: T };
type ContainerA = Container<string | number>;
type ContainerB = Container<string> | Container<number>
type ContainerC<T extends string | number> = Container<T>;

Note also that Spread is a syntax rule in JavaScript. Its usage in your question is confusing.