Typescript useful utility types

utilityTypes.d.ts

type Prefix<TModel extends {}, P extends string> = {
    [Key in string & keyof TModel as `${P}${Capitalize<Key>}`]: TModel[Key];
}

type Suffix<TModel extends {}, S extends string> = {
    [Key in string & keyof TModel as `${Key}${Capitalize<S>}`]: TMOdel[Key];
}

// EnsureProps<{}> = never
// EnsureProps<Person> = Person
type EnsureProps<TModel> = keyof TModel extends never ? never : TModel;

// copied from https://stackoverflow.com/a/69288824/75642
export type Expand<T> = T extends (...args: infer A) => infer R
    ? (...args: Expand<A>) => Expand<R>
    : T extends infer O
    ? { [K in keyof O]: O[K] }
    : never;

export type ExpandRecursively<T> = T extends (...args: infer A) => infer R
    ? (...args: ExpandRecursively<A>) => ExpandRecursively<R>
    : T extends object
    ? T extends infer O
        ? { [K in keyof O]: ExpandRecursively<O[K]> }
        : never
    : T;
    
// Use as:
// type SomeExpandedType = Expand<SomeConvolutedType>;
// type SomeFullyExpandedType = ExpandRecursively<SomeConvolutedType>;