use 5.010;

##</code><code>##

use feature 'switch';

##</code><code>##

no if $] >= 5.018, warnings => "experimental::feature_name";

##</code><code>##

no if $] >= 5.018, warnings => "experimental::switch";

##</code><code>##

Unknown warnings category 'experimental::switch' at ...
BEGIN failed--compilation aborted at ...

##</code><code>##

no if $] >= 5.018, warnings => "experimental::smartmatch";

##</code><code>##

given is experimental at ...
when is experimental at ...
when is experimental at ...
when is experimental at ...

##</code><code>##

#!/usr/bin/env perl -l

use 5.010;
use strict;
use warnings;
no if $] >= 5.018, warnings => "experimental::smartmatch";

print '*** test1() ***';
print "$_ is ", test1($_) for 0 .. 4;

print '*** test2() ***';
print "$_ is ", test2($_) for 0 .. 4;

print '*** test3() ***';
print "$_ is ", test3($_) for 0 .. 4;

sub test1 {
    my ($var) = @_;

    my $i;

    given ($var) {
        when (1) { $i = 'One' }
        when (2) { $i = 'Two' }
        when (3) { $i = 'Three' }
        default  { $i = 'Other' }
    }

    return $i;
}

sub test2 {
    my ($var) = @_;

    return $var == 1 ? 'One'
         : $var == 2 ? 'Two'
         : $var == 3 ? 'Three'
         :             'Other';
} 

sub test3 {
    state $word_for = {qw{1 One 2 Two 3 Three}};
    return $word_for->{+shift} || 'Other';
}

##</code><code>##

*** test1() ***
0 is Other
1 is One
2 is Two
3 is Three
4 is Other
*** test2() ***
0 is Other
1 is One
2 is Two
3 is Three
4 is Other
*** test3() ***
0 is Other
1 is One
2 is Two
3 is Three
4 is Other