I’m trying to understand Ramda’s transducers. Here’s a slightly modified example from the docs:

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 ]

But what if I want to sum the elements of the resulting array? The following (just adding `R.sum`

into `R.compose`

) doesn’t work:

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

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## Answer

I’d do something like this, just accumulate on top of an initial 0 value

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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