When mapping on a type, how to make the keys not readonly?

Question

The question is as simple as the title suggests: how do I make keys writable (instead of readonly) when mapping from a type that is Readonly?

f.e.

type Foo = Readonly<{
  foo: number
  bar: number
}>

type Bar = /* how to copy the Foo type, but make it writable? */

Answer 1

Use -readonly to remove readonly when mapping e.g.

export type Foo = Readonly<{
  foo: number
  bar: number
}>;

export type Writeable<T> = {
  -readonly [P in keyof T]: T[P];
};

export type Bar = Writeable<Foo>;
let x:Bar = {
  foo: 123,
  bar: 456
}
x.bar = 123; // OK 

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