How can a TypeScript generic be utilized to limit function parameters while not retaining the type of the argument?

edit

One way to limit function parameters while not retaining the type of the argument is to use a type parameter with a constraint that specifies a union of allowed types.

For example, suppose we have a function that takes two arguments, a and b, and we want to limit a to be a string or number, but we don't want to retain the specific type of a in the return type:

function myFunc<T extends string | number>(a: T, b: any) {
  // do something with a and b
}

myFunc("hello", 42); // OK
myFunc(true, null); // Error: 'true' is not assignable to string | number

In this example, T is a type parameter with a constraint of string | number, which limits the possible types for a. However, the return type of myFunc does not include T, so the specific type of a is not retained.