最终 R.sum 的 ramda 传感器

Question

我正在尝试了解 Ramda 的转换器。这是文档中的一个稍微修改过的示例：

const numbers = [1, 2, 3, 4];
const isOdd = (x) => x % 2 === 1;
const firstFiveOddTransducer = R.compose(R.filter(isOdd), R.take(5));
R.transduce(firstFiveOddTransducer, R.flip(R.append), [], R.range(0, 100)); //=> [ 1, 3, 5, 7, 9 ]

但是如果我想对结果数组的元素求和怎么办？以下（只需将 R.sum 添加到 R.compose 中）不起作用：

const firstFiveOddTransducer = R.compose(R.filter(isOdd), R.take(5), R.sum);

Answer 1

我会做这样的事情，只是在初始 0 值之上累积

const list = [1, 2, 3, 4, 5];
const isOdd = R.filter(n => n % 2);

const transducer = R.compose(isOdd);

const result = R.transduce(transducer, R.add, 0, list);

console.log(
  'result',
  result,
);

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最终 R.sum 的 ramda 传感器

ramda transducers with final R.sum

javascript

functional-programming

transducer

ramda.js