It isn't obvious that exists @haystack{qw(aa bb cc dd)} should provide an "ANY" test. Some might think an "ALL" test would be correct. Thus, it definitely doesn't belong in core.

I'd suggest using any for clarity and to remove the need for !! (and the risk that one of your keys might be "0").

use List::Util qw(any first);
my %haystack; @haystack{'aa'..'ff',"0"} = ();
say any { exists $haystack{$_} } qw(aa bb cc dd);

say any { exists $haystack{$_} } qw(zz 0);       # OK
say !! first { exists $haystack{$_} } qw(zz 0);  # Oops!

[download]

Good Day,
    Dean

In reply to Re: Why doesn't exist work with hash slices? by duelafn
in thread Why doesn't exist work with hash slices? by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.