locale.ts

type LocaleStrings<K extends string> = {
    [key in K]: string
}

type LocaleArea<A extends string, S extends string | number> = {
    [K in `@${A}/${S}`]: string
}

const area = <A extends string, K extends string>(area: A, strings: LocaleStrings<K>): LocaleArea<A, K> =>
    Object.keys(strings)
        .map(key => ({ [`@${area}/${key}`]: strings[key] }))
        .reduce((x, y) => ({ ...x, ...y }), {}) as LocaleArea<A, K>

const en_US = {
    ...area('Contact', {
        'GitHub': 'Visit @icorbrey on GitHub',
        'LinkedIn': 'Visit /in/isaaccorbrey on LinkedIn',
        'Twitter': 'Visit @icorbrey on Twitter',
    })
}

type Locale = typeof en_US
type LocaleKeys = keyof Locale

const locale = en_US

const localized = (key: LocaleKeys) =>
    en_US[key] ?? `[[${key}]]`

const mockLocalized = (key: LocaleKeys) =>
    key as string

console.log(localized('@Contact/GitHub'))