#!/usr/bin/env perl -l

use strict;
use warnings;

my $shift = 'E';
my @x = \ (qw{A B C D});
test_shift(@x);

sub test_shift {
    print ${+shift};
    print ${shift()};
    print ${shift @_};
    print ${shift(@_)};
    print ${shift};
}

##</code><code>##

Ambiguous use of ${shift} resolved to $shift at ./junk line 15.
A
B
C
D
E

##</code><code>##

$ perl -Mstrict -Mwarnings -le 'print (1==0) ? "true" : "false"'
print (...) interpreted as function at -e line 1.
Useless use of a constant ("true") in void context at -e line 1.
Useless use of a constant ("false") in void context at -e line 1.

$ perl -Mstrict -Mwarnings -le 'print +(1==0) ? "true" : "false"'
false

##</code><code>##

$ perl -Mstrict -Mwarnings -MData::Dump -e 'dd [map { my $y = uc; {$y => 1} } "a".."c"]'
["A", 1, "B", 1, "C", 1]

$ perl -Mstrict -Mwarnings -MData::Dump -e 'dd [map { my $y = uc; +{$y => 1} } "a".."c"]'
[{ A => 1 }, { B => 1 }, { C => 1 }]

##</code><code>##

$ perl -Mstrict -Mwarnings -le 'use constant X => "a"; my %h = (a => 1); print $h{X}'
Use of uninitialized value in print at -e line 1.

$ perl -Mstrict -Mwarnings -le 'use constant X => "a"; my %h = (a => 1); print $h{+X}'
1