my $consider = 'foo';
${{
    bar => sub { print "Barred!\n" },
    foo => sub { print "Fooed for thought...\n" }
}}{$consider}();

##</code><code>##

{
  my $continue = 1;
  $_->[1]() for grep {
    my ($cond, $then, $break)=@$_;
    local $_='boz'; # This is your given
    $continue and
    $cond->() and do { $continue = !defined $break; 1}
  }
  [sub {/z/}, sub { print "Hi!\n" }],
  [sub {/o/}, sub { print "Oh!\n" }, 'break'],
  [sub {1},   sub { print "This is the default\n" }]
  ;
}

##</code><code>##

{
  my $continue = 1;

  sub given ($$) {
    local $_ = shift;
    my $next = shift;
    my ($cond, $then);
    while ($next) {
      ($cond, $then, $next) = @$next;
      $then->() if $cond->() and $then;
      $continue or last;
    }
  }

  sub when (&$)  { [$_[0], @{$_[1]}] }
  sub then (&;$) { [@_] }
  sub default(&) { [@_] }
  sub done() { $continue = 0 }
  sub isit ($$)  { my @args=@_; [sub { $_ eq $args[0] }, @{$args[1]}] }
}

given 'baz',
  isit 'baz', then { print "String match!\n" }
  when {/z/}  then { print "Hi!\n" }
  when {/o/}  then { print "Oh!\n"; done }
  default { print "This is the default\n" }
;