In Control flow§

See primary documentation in context for next.

The next command starts the next iteration of the loop. So the code

my @x = 1, 2, 3, 4, 5;
for @x -> $x {
    next if $x == 3;
    print $x;
}

prints "1245".

You can also use next in a map: the above example then looks like:

my @x = 1, 2, 3, 4, 5;
print @x.map: -> $x {
    next if $x == 3;
    $x
}

prints "1 2 4 5" because a space is added between entries of a Seq when it is stringified. Note that that print was not put inside the block of the map, as it generally considered bad practice to run a map for its side-effects (in this case, the print.

If the NEXT phaser is present, it runs before the next iteration:

my Int $i = 0;
while ($i < 10) {
  if ($i % 2 == 0) {
    next;
  }

  say "$i is odd.";

  NEXT {
    $i++;
  }
}
# OUTPUT: «1 is odd.␤3 is odd.␤5 is odd.␤7 is odd.␤9 is odd.␤»

In version 6.e.PREVIEW (available as of the 2021.07 Rakudo compiler release), it is also possible to return a value with the next statement. This is particularly useful when using it in a map:

my @x = 1, 2, 3, 4, 5;
print @x.map: -> $x {
    next 42 if $x == 3;
    $x
}

prints "1 2 42 4 5".

In a whenever block, next immediately exits the block for the current value:

react {
    whenever Supply.interval(1) {
        next if .is-prime;
        say $_;
        done if $_ == 4;
    }
}

prints "0", "1" and "4" - integers from 0 to 4 with primes skipped.

*Since version 6.d, the next command in a loop that collects its last statement values returns Empty for the iterations they run on.*