AI solution for TypeScript puzzle on BFE.dev
2. implement Required<T>

Here is a possible solution to implement MyRequired<T>:

type MyRequired<T> = {
  [P in keyof T]-?: T[P]
}

In this solution, we use the -? modifier in the mapped type syntax to make all properties required.

By applying MyRequired<Foo> to the example above, we get:

const a: MyRequired<Foo> = {}
// Error: Property 'a' is missing and required in type 'MyRequired<Foo>'

const b: MyRequired<Foo> = {
  a: 'BFE.dev'
}
// Error: Property 'b' is missing and required in type 'MyRequired<Foo>'

const c: MyRequired<Foo> = {
  b: 123
}
// Error: Property 'c' is missing and required in type 'MyRequired<Foo>'

const d: MyRequired<Foo> = {
  b: 123,
  c: true
}
// Error: Property 'a' is missing and required in type 'MyRequired<Foo>'

const e: MyRequired<Foo> = {
  a: 'BFE.dev',
  b: 123,
  c: true
}
// valid

As expected, all properties of Foo are now required in MyRequired<Foo>.