https://stackoverflow.com/questions/44360568/typescript-generics

44360568.ts

    type DataProvider<TKey extends string, TData> = {
      getData(): TData
    }
    
    type ProvidedData<K1 extends string, T1> = { [key in K1]: T1 }
    
    function getDataFromProviders<K1 extends string, T1>(p1: DataProvider<K1, T1>): ProvidedData<K1, T1>
    function getDataFromProviders<K1 extends string, T1, K2 extends string, T2>(p1: DataProvider<K1, T1>, p2: DataProvider<K2, T2>): ProvidedData<K1, T1> & ProvidedData<K2, T2>
    function getDataFromProviders(...providers: DataProvider<any, any>[]): {[name: string]: any } {
      const result = {};
    
      for (const name of Object.getOwnPropertyNames(providers)) {
          result[name] = providers[name].getData();
      }
    
      return result;
    }
    
    const tenProvider : DataProvider<"ten", number> = {
      getData: () => 10
    }
    
    const greetProvider : DataProvider<"greet", number> = {
      getData: () => 'hi'
    }
    
    const values = getDataFromProviders(
      tenProvider,
      greetProvider
    )