example.ts

// email.ts

import { Email } from './mobile';
export type Email = string & { __phantom_1549009918142: never }

export const createEmail = (input: string): Email | Error => {
 const pattern = /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0–9]{1,3}\.[0–9]{1,3}\.[0–9]{1,3}\.[0–9]{1,3}])|(([a-zA-Z\-0–9]+\.)+[a-zA-Z]{2,}))$/
 if(pattern.test(input)) return createOf<Email, string>(input)
 else return new Error(`invalid email format: ${input}`)
}

// signup.ts

import { Email, createEmail } from './email'

type Account = {
    email: Email,
    password: string,
    createdAt: Date
}

function signup(inputForm): Account {

    try {
        
        const email: Email = createEmail(inputForm.email)

        return {
            email,
            password: inputForm.password,
            createdAt: new Date()
        }

    } catch (ex) {
        
        console.error(`There has been an error during signup`, ex)
        
    }

}