Type alias Variant<U>

Utility type for defining a keyed union type as in IPLD Schema. In practice this just works around typescript limitation that requires discriminant field on all variants.

type Result<T, X> =
  | { ok: T }
  | { error: X }

const demo = (result: Result<string, Error>) => {
  if (result.ok) {
  //  ^^^^^^^^^ Property 'ok' does not exist on type '{ error: Error; }`
  }
}
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Using Variant type we can define same union type that works as expected:

type Result<T, X> = Variant<{
  ok: T
  error: X
}>

const demo = (result: Result<string, Error>) => {
  if (result.ok) {
    result.ok.toUpperCase()
  }
}
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