AI solution for TypeScript puzzle on BFE.dev
13. implement InstanceType<T>

Here's one possible implementation of MyInstanceType<T>:

type MyInstanceType<T extends new (...args: any) => any> = T extends new (...args: any) => infer R ? R : any;

Explanation:

• MyInstanceType is a type that takes a type parameter T that extends a constructor function (i.e., a type with a new signature).
• The type MyInstanceType<T> evaluates to the type of the instance that T creates.
• The implementation uses conditional types (T extends new (...args: any) => infer R ? R : any) to extract the return type R of the constructor function T, and return it as the instance type. If T is not a constructor function, the type any is returned instead.