Immutability

Immutable restrictions on function input parameters usually greatly increase the runtime burden.

This library provides a tool type named Immutable, tries to make this restriction with typescript and then there would be no performance loss when running.

TIP

Immutable has the second parameter to specify types to ignore.

// `Immutable` will expand the input type.
// `File` is a builtin type, which is not equal to expaned `File`.
// You may need to ignore `File`, or it cannot satisfies another `File`.
type Res = Immutable<
  {
    file: File
  },
  File
>
// Res = {
//   readonly file: File
// }