ジェネレータで無限を手玉に取る修行

0-util.php

<?php

function map(Closure $callback, iterable $iter): Generator
{
    foreach ($iter as $k => $v) {
        yield $k => $callback($v);
    }
}

function take(int $n, iterable $iter): Generator
{
    $i = 0;
    foreach ($iter as $k => $x) {
        if ($n <= $i++) { break; }
        yield $k => $x;
    }
}

1-fizzbuzz-A.php

<?php

function fizzbuzz_genA()
{
    for ($i = 1; $i <= 100; $i++) {
        yield fizzbuzz($i);
    }
}

foreach (fizzbuzz_genA() as $fizzbuzz) {
    echo $fizzbuzz, PHP_EOL;
}

2-fizzbuzz-B.php

<?php

function fizzbuzz_genB(int $n, int $m)
{
    yield from map(Closure::fromCallable('fizzbuzz'), xrange($n, $m));
}


foreach (fizzbuzz_genB(20, 80) as $fizzbuzz) {
    echo $fizzbuzz, PHP_EOL;
}

3-fizzbuzz-C.php

<?php

function fizzbuzz_genC(int $n)
{
    while (true) {
        yield fizzbuzz($n++);
    }
}

foreach (take(100, fizzbuzz_genC(60)) as $fizzbuzz) {
    echo $fizzbuzz, PHP_EOL;
}