Function reduceWhile

repos/effect/packages/effect/src/Sink.ts:1218–1245

(
  initial: LazyArg<S>,
  predicate: Predicate<S>,
  f: (s: S, input: In) => S
)

  f: (a: A) => Sink<A1, In1, L1, E1, R1>
): Sink<A1, In & In1, L | L1, E | E1, R | R1> =>
  fromTransform((upstream, scope) => {
    let upstreamDone = false
    const pull = Effect.catchCause(upstream, (cause) => {
      upstreamDone = true
      return Effect.failCause(cause)
    })
    return Effect.flatMap(
      self.transform(pull, scope),
      ([a, leftover]) =>
        f(a).transform(
          Effect.suspend(() => {
            if (leftover) {
              const arr = leftover as Arr.NonEmptyReadonlyArray<In1>
              leftover = undefined
              return Effect.succeed(arr)
            } else if (upstreamDone) {
              return Cause.done()
            }
            return upstream
          }),
          scope
        )
    )
  }))

/**
 * A sink that reduces input elements from the provided `initial` state with
 * `f` while the specified `predicate` returns `true`.
 *
 * @category folding
 * @since 4.0.0