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@ericelliott
Created April 21, 2020 22:03
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for-await-of-transducers
const compose = (...fns) => x => fns.reduceRight((y, f) => f(y), x);
function map(f) {
return async function*(values) {
for await (const x of values) {
yield f(x);
}
};
}
function filter(f) {
return async function*(values) {
for await (const x of values) {
if (f(x)) yield x;
}
};
}
const double = x => x * 2;
const isEven = x => x % 2 === 0;
const doubleEvens = compose(
filter(isEven),
map(double)
);
async function* source() {
let n = 1;
while (true) {
//eslint-disable-next-line
yield await new Promise(resolve => setTimeout(() => resolve(n++), 100));
}
}
async function go() {
const iter = doubleEvens(source());
const limit = 5;
let counter = 0;
while (counter < limit) {
const { value } = await iter.next();
console.log(value);
counter++;
}
}
go();
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