Typescript rest operator arguments keyof object

Question

How do you define function arguments with the rest operator to be an array of keys defined in a given type? I also need the return object to be an object shaped by the given argument keys & their corresponding types from the T type.

  type MyType<T> = {
    ...,

    // This is my struggle function
    myCallableFunction(...keys: keyof T[]) => object
  }

Answer 1

The answer I was looking for ended up using Pick :

type MyType<T> = {
    myFunctionCall<U extends keyof T>(...keys: U[]): Pick<T, U>;
};

The object that myFunctionCall returns will have the listed properties from T with their value types as defined on T . So if T has the properties a and b of type number and c and d of type string , then the return type of theObject.myFunction("a", "c") will be Pick<T, "a" | "c"> Pick<T, "a" | "c"> , which is {a: number; c: string;} {a: number; c: string;} (in that example).

Playground example