Run results for: .map.filter vs transducers v2

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.83 Safari/537.36

Browser: Chrome 85

Operating system: Windows

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
xform	1.4 Ops/sec
classic	0.3 Ops/sec
classic v2	585.6 Ops/sec
xform2	475.9 Ops/sec

HTML Preparation code:

<script src='https://cdnjs.cloudflare.com/ajax/libs/ramda/0.27.0/ramda.min.js'></script>
<script>
  const data = [...Array(10000).keys()].map(() => ({
    val: Math.floor(Math.random() * 10000)
}))

const isEven = i => i % 2 === 0

// Transducers
const mapping = f => reducing => (result, input) => reducing(result, f(input))
const filtering = pred => reducing => (result, input) => pred(input) ? reducing(result, input) : result
const uniq = () => reducing => {
    let pv
    return (result, input) => {
        const prior = pv
        pv = input
        return prior === input ? result : reducing(result, input)
    }
}
const xform = R.compose(
    mapping(x => x.val),
    mapping(x => x + 2),
    uniq(),
    filtering(isEven)
);

const transduce = (xform, f, init, coll) => coll.reduce(xform(f), init)
const conj = (a, b) => !!b ? [...a, b] : a
const conjm = (a, b) => !!b ? (a.push(b) && a) : a
  
const print = (label, res) => console.log(label, res.reduce((a, b) => a + b, 0))
</script>

Tests:

xform
transduce(xform, conj, [], data)
classic
data .map(item => item.val) .map(val => val + 2) .reduce((acc, val) => acc.length !== 0 && acc[acc.length - 1] === val ? acc : [...acc, val], []) .filter(isEven)
classic v2
data .map(item => item.val) .map(val => val + 2) .reduce((acc, val) => acc.length !== 0 && acc[acc.length - 1] === val ? acc : (acc.push(val) && acc), []) .filter(isEven)
xform2
transduce(xform, conjm, [], data)

Run results for: .map.filter vs transducers v2

xform

classic

classic v2

xform2