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@kolharsam
Last active Jan 14, 2021
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Dabbling with Transducers in JS
const list = [1,2,3,4,5,6,7,8,9];
const inc = x => x + 1;
const isOdd = x => x % 2 !== 0;
console.log(list.map(inc));
console.log(list.filter(isOdd))
console.log(list.map(inc).filter(isOdd))
console.log(list.reduce((acc, val) => {
if (isOdd(inc(val))) {
return [...acc, inc(val)];
}
return acc;
}, []));
const comp = (...fns) => x =>
fns.reduceRight((prevAnswer, fn) => fn(prevAnswer), x);
const compT = (...fns) => (acc, val) => {
const r = fns.reduceRight((prevAnswer, fn) => {
return prevAnswer.reduce((a,v) => {
return fn(a, v);
}, []);
}, [val]);
if (!r) {
return acc;
}
if (Array.isArray(r)) {
return [...acc, ...r];
}
return [...acc, r];
};
const compMapFilter = comp(isOdd, inc);
const cmpRes = list.reduce((acc, val) => {
const res = compMapFilter(val);
if (res) {
return [...acc, val];
};
return acc;
}, []);
console.log(cmpRes)
const mapT = mappingFn => (acc, val) => {
return [...acc, mappingFn(val)];
};
const filterT = predicate => (acc, val) => {
if (predicate(val)) {
return [...acc, val];
}
return acc;
};
const compTs = compT(filterT(isOdd), mapT(inc));
console.log(list.reduce(mapT(inc), []));
console.log(list.reduce(filterT(isOdd), []));
console.log(list.reduce(compTs, []));
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