roolic's answer is flawed. Building a hash is smart, but building it over and over again is dumb. Even

sub exists { 
  my ($array, $value) = @_; 
  return grep $_ eq $value, @$array;
}

exists( $arr_ref, $value ) ? 'yes' : ''
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would be better than

sub exists { 
  my ($array, $value) = @_; 
  my %all_vals = map { $_=>1 } @{$array}; 
  return $all_vals{$value};
}

exists( $arr_ref, $value ) ? 'yes' : ''
[download]