Snake case to CammelCase

template-literal-type.ts

interface Example {
    first_name: string,
    last_name: string,
    home_town: string,
}

type CamelizeString<T extends PropertyKey> = T extends string ? string extends T ? string :
    T extends `${infer F}_${infer R}` ? `${F}${Capitalize<CamelizeString<R>>}` : T : T;

type Camelize<T> = { [K in keyof T as CamelizeString<K>]: T[K] }

type CamelizeExample = Camelize<Example>;
/* type CamelizeExample = {
    firstName: string;
    lastName: string;
    homeTown: string;
} */

const e: Camelize<Example> = {
    firstName: 'string',
    lastName: 'string',
    homeTown: 'string'
}