You can accomplish your task using Prototypes. In fact, from the linked documentation,
here's a reimplementation of the Perl grep operator: 

sub mygrep (&@) {
    my $code = shift;
    my @result;
    foreach $_ (@_) {
        push(@result, $_) if &$code;
    }
    @result;
}

[download]

Update: Your example would be called as: print join ",", mygrep {$_ % 2 == 0} 0..10; Note the deviation from the proposed use case. I'd initially missed the spec for "automatically put [ting] it in an implicit block"

In reply to Re: make subroutine that takes expression as implicit block as first arg by kennethk
in thread make subroutine that takes expression as implicit block as first arg by myuserid7

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