Packages

const parse = (input: string): Result<number, 'not_a_number'> => {
  const value = Number(input)
  return Number.isNaN(value)
    ? Result.failure('not_a_number')
    : Result.success(value)
}

const result = parse(raw)
if (result.status === 'failure') return result.error
Worked out by the compiler: 'not_a_number'
result.data
Worked out by the compiler: number

export const themeStore = createThemePreferenceStore({
  storageKey: 'app:theme'
})

// vite.config.ts: runs before the first paint
plugins: [themePreferencePlugin(themeStore)]

themeStore.setPreference('dark')
Worked out by the compiler: <html data-theme="dark">
Worked out by the compiler: dark theme-color: media="all"
Worked out by the compiler: light theme-color: media="not all"

const locale = readRecognizedText({
  key: 'app:locale',
  isRecognized: isLocale
})

if (locale.status === 'failure') {
  locale.error
  Worked out by the compiler: 'unavailable' | 'unrecognized'
} else {
  locale.data
  Worked out by the compiler: 'en' | 'fr' | null
}