Hm, not sure of what you are trying to do, but assuming I understood, one possibility might be using the smart match: 
  DB<38> use v5.10.0;

  DB<39> $var = 7;

  DB<40> @a = qw/ 4 6 7 9 3/;

  DB<41>  print "yes" if $var ~~  @a;
yes

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(I know it has been deprecated and I would certainly not use that for production code that is supposed to last, but there are cases where you might want to use it nonetheless because it is a short-life project, for example.)

grep is an alternative: 

print "yes" if grep { $var == $_} @a;

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Or you could use the any function of List::Util module (if your version of that module is recent enough, version 1.33 or above, I think), with just about the same syntax as the grep line above. This should often be faster than grep because any will short-circuit as soon as it has found a matching element, and grep won't.

If your version of List::Util is too old, then try any in List::MoreUtils, any has been around with it for longer. Or you could implement it yourself with List::Util's reduce function (the reduce documentation shows basically how to do it).

With reduce, you could even implement an iterator-based lazy version of grep that will short-circuit for you (but will usually not be faster, except when the list is long and the item found early in the list).

Or you might turn to Perl 6. ;-)

But all the above might just be off-topic if I misunderstood your requirement. Please explain further.

In reply to Re: Create a new operator, get LHS by Laurent_R
in thread Create a new operator, get LHS by stevieb

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