generators.js

'use strict';

function *fibonacci(a=0,b=1) {
    while (true) {
        yield a; [a,b] = [b,a+b]
    }
}

function *odd(f) {
    while (true) {
        let v = f.next().value
        if (v & 1) { yield v }
    }
}

function *cats() {
    while (true) {
        yield 'alice'
        yield 'bob'
        yield 'eve'
    }
}

function *transpose(f,g) {
    while (true) {
        yield [f.next().value, g.next().value]
    }
}

function *intersperse(a,f) {
    while (true) {
        yield a
        yield f.next().value
    }
}

function *get(n,f) {
    while(n--) {
        let v = f.next().value
        yield v
    }
}

console.log( "The first 10 odd fibonacci numbers:\n", [...get(10, odd(fibonacci()) )], "\n" )
console.log( "20 fibonacci numbers insterspersed with zeroes:\n", [...get(20, intersperse(0,fibonacci()) )], "\n" )
console.log( "My first two cats:\n", [...get(2, cats() )], "\n" )
console.log( "My three cats, transposed with the fibonacci sequence:\n", [...get(10, transpose(cats(),fibonacci()) )], "\n" );

let [x,y] = transpose(cats(),fibonacci())
console.log( "Or using decomposition:\n", [y,x])