Lifting out computation from iteration

pure_iteration.php

<?php
declare(strict_types=1);

function uppercaseWordsImperative(array $words): void {
    foreach ($words as $word) {
        $word = strtoupper($word);
        echo $word.' ';
    }
}

uppercaseWordsImperative(['foo', 'bar', 'baz']);

echo PHP_EOL;

// [String] -> [String]
function uppercaseWords(array $words): Generator {
    foreach ($words as $word) {
        yield strtoupper($word);
    }
}

// [String] -> IO ()
function uppercaseWordsImperativeShell(array $words): void {
    foreach (uppercaseWords($words) as $word) {
        echo $word.' ';
    }
}

uppercaseWordsImperativeShell(['foo', 'bar', 'baz']);