mapUntil.ts

const mapUntil = function*<T, K>(
  fn: (a: T) => K,
  p: (a: K) => boolean,
  xs: T[]
): IterableIterator<K> {
  for (const x of xs) {
    const result = fn(x)
    if (!p(result)) {
      break
    }
    yield result
  }
}

const asyncMapUntil = async function*<T, K>(
  fn: (a: T) => K,
  p: (a: K) => boolean,
  xs: T[]
): AsyncIterableIterator<K> {
  for (const x of xs) {
    const result = await fn(x)
    if (!p(result)) {
      break
    }
    yield result
  }
}

const asyncConsume = async <T>(xs: AsyncIterableIterator<T>) => {
  const results = []
  for await (const x of xs) {
    results.push(x)
  }
  return results
}