Function extend

packages/effect/src/internal/configProvider.ts:201–224

(
  leftDef: (n: number) => A,
  rightDef: (n: number) => B,
  left: ReadonlyArray<A>,
  right: ReadonlyArray<B>
)

}

const extend = <A, B>(
  leftDef: (n: number) => A,
  rightDef: (n: number) => B,
  left: ReadonlyArray<A>,
  right: ReadonlyArray<B>
): [ReadonlyArray<A>, ReadonlyArray<B>] => {
  const leftPad = Arr.unfold(
    left.length,
    (index) =>
      index >= right.length ?
        Option.none() :
        Option.some([leftDef(index), index + 1])
  )
  const rightPad = Arr.unfold(
    right.length,
    (index) =>
      index >= left.length ?
        Option.none() :
        Option.some([rightDef(index), index + 1])
  )
  const leftExtension = concat(left, leftPad)
  const rightExtension = concat(right, rightPad)
  return [leftExtension, rightExtension]
}

const appendConfigPath = (path: ReadonlyArray<string>, config: Config.Config<unknown>): ReadonlyArray<string> => {
  let op = config as _config.ConfigPrimitive