Deep Readonly

by Anthony Fu @antfu

Implement a generic DeepReadonly<T> which make every parameter of an object - and its sub-objects recursively - readonly.

Array is not required to be considered in this challenges.

For example

type X = { 
  x: { 
    a: 1
    b: 'hi'
  }
  y: 'hey'
}

type Expected = { 
  readonly x: { 
    readonly a: 1
    readonly b: 'hi'
  }
  readonly y: 'hey' 
}

const todo: DeepReadonly<X> // should be same as `Expaceted`