grep evaluates an expression, unlike split which matches a pattern. Consider: 

use strict;
use warnings;

my $re = qr/y/;
$_ = 'yep';
print /y/;
print "\n".$re;
print "\n"./$re/;

[download]

which prints:

1
(?-xism:y)
1

[download]
DWIM is Perl's answer to Gödel

In reply to Re: Grep matches all elements if compiled regex is passed as EXPR by GrandFather
in thread Grep matches all elements if compiled regex is passed as EXPR by isotope

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