Online PHP editor | output for tBY4O

@ 2016-05-24T18:49:26Z

<?php

function powerSet(Iterator $iterator){
    if(!$iterator->valid()){
        return yield new EmptyIterator();
    }
    $one = $iterator->current();
    $rest = new NoRewindIterator($iterator);
    $rest->next();
    foreach(powerSet($rest) as $set){
        $set = iterator_to_array($set);
        yield new ArrayIterator($set);
        
        // why does this work
        yield (function($set, $one){
            yield from array_merge($set, [$one]);
        })($set, $one);

        // but this doesn't?
        // yield (function($set, $one){
        //     yield from $set;
        //     yield $one;
        // })($set, $one);
    }
}

function baz(){
    yield 1;
    yield 2;
    yield 3;
    yield 4;
}
$sets = powerSet(baz());


foreach($sets as $i => $set){
    echo $i+1 . " {";
    $arr = iterator_to_array($set);
    echo implode(", ", $arr);
    echo "}\n";
}

Output for 7.0.0 - 7.0.20, 7.1.0 - 7.1.20, 7.2.0 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.4, 8.3.6: 1 {} 2 {1} 3 {2} 4 {2, 1} 5 {3} 6 {3, 1} 7 {3, 2} 8 {3, 2, 1} 9 {4} 10 {4, 1} 11 {4, 2} 12 {4, 2, 1} 13 {4, 3} 14 {4, 3, 1} 15 {4, 3, 2} 16 {4, 3, 2, 1}
Output for 8.3.5: Warning: PHP Startup: Unable to load dynamic library 'sodium.so' (tried: /usr/lib/php/8.3.5/modules/sodium.so (libsodium.so.23: cannot open shared object file: No such file or directory), /usr/lib/php/8.3.5/modules/sodium.so.so (/usr/lib/php/8.3.5/modules/sodium.so.so: cannot open shared object file: No such file or directory)) in Unknown on line 0 1 {} 2 {1} 3 {2} 4 {2, 1} 5 {3} 6 {3, 1} 7 {3, 2} 8 {3, 2, 1} 9 {4} 10 {4, 1} 11 {4, 2} 12 {4, 2, 1} 13 {4, 3} 14 {4, 3, 1} 15 {4, 3, 2} 16 {4, 3, 2, 1}
Output for 5.5.0 - 5.5.35, 5.6.6 - 5.6.28: Parse error: syntax error, unexpected 'new' (T_NEW) in /in/tBY4O on line 5
Process exited with code 255.

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