NAME
    Loop::Util - loop helper keywords

SYNOPSIS
      use Loop::Util;
  
      my @array = qw(foo bar baz quux);
  
      for my $item (@array) {
  
        iffirst {
          print "Items\n";
          print "-" x length($item), "\n";
        }
    
        print "$item\n";
    
        iflast {
          print "-" x length($item), "\n";
          print "Count: ", scalar(@array), "\n";
        }
      }

DESCRIPTION
    This module adds statement keywords:

    *   `loop BLOCK`, `loop (EXPR) BLOCK`

        `loop` introduces new loop forms.

          loop { ... }
          loop(3) { ... }
          loop(get_number()) { ... }

        `loop` also supports a single-statement form:

          loop process_input();
          loop(3) process_input();

        Parentheses are required around the loop count expression. If no count
        is given, the loop is infinite, but `last` can be used to jump out of
        the loop. (The `next` and `redo` keywords also work as expected.)

    *   `iffirst [LABEL] BLOCK [else BLOCK]`

        Runs `BLOCK` only on the first loop iteration; if an `else` block is
        present it runs for subsequent iterations.

        When `LABEL` is present, `iffirst` checks that labeled loop context
        instead of the innermost loop. This is useful in nested loops:

          OUTER: loop(2) {
            loop(3) {
              iffirst OUTER { say "hi" }
            }
          }

        `iffirst` works in `loop{}` loops, and also in `for`/`foreach` loops
        over arrays and lists. Calling `iffirst` in other loop kinds throws a
        runtime error.

    *   `iflast [LABEL] BLOCK [else BLOCK]`

        Runs `BLOCK` only on the last loop iteration; if an `else` block is
        present it runs for not-last iterations.

        When `LABEL` is present, `iflast` checks that labeled loop context
        instead of the innermost loop.

        `iflast` works in finite `loop{}` loops, and also in `for`/`foreach`
        loops over arrays and lists. Calling `iflast` in other loop kinds
        throws a runtime error.

    *   `ifodd [LABEL] BLOCK [else BLOCK]`

        Runs `BLOCK` for odd-numbered iterations (1st, 3rd, 5th...). If an
        `else` block is present, it runs on even-numbered iterations.

        Note that if you loop through an array, the first iteration (an odd
        iteration) has index number 0 (an even number).

        When `LABEL` is present, `ifodd` checks that labeled loop context
        instead of the innermost loop.

        `ifodd` works in `loop{}` loops, and also in `for`/`foreach` loops
        over arrays and lists. Calling `ifodd` in other loop kinds throws a
        runtime error.

    *   `ifeven [LABEL] BLOCK [else BLOCK]`

        Runs `BLOCK` for even-numbered iterations (2nd, 4th, 6th...). If an
        `else` block is present, it runs on odd-numbered iterations.

        Note that if you loop through an array, the first iteration (an odd
        iteration) has index number 0 (an even number).

        When `LABEL` is present, `ifeven` checks that labeled loop context
        instead of the innermost loop.

        `ifeven` works in `loop{}` loops, and also in `for`/`foreach` loops
        over arrays and lists. Calling `ifeven` in other loop kinds throws a
        runtime error.

    *   `__IX__`

        Psuedo-constant that returns the current zero-based index of the loop.

        It should work for `loop{}` loops as well as `for`/`foreach` loops
        over arrays or lists. In other contexts where no index can be
        determined, it returns `undef`.

BUGS
    Please report any bugs to
    <https://github.com/tobyink/p5-loop-util/issues>.

SEE ALSO
    Acme::Loopy, Syntax::Keyword::Loop.

AUTHOR
    Toby Inkster <tobyink@cpan.org>.

COPYRIGHT AND LICENCE
    This software is copyright (c) 2026 by Toby Inkster.

    This is free software; you can redistribute it and/or modify it under the
    same terms as the Perl 5 programming language system itself.

DISCLAIMER OF WARRANTIES
    THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
    WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
    MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.