#!/usr/bin/perl
use strict;
use warnings;

sub x { local$,=" "; print "$_[ 0 ]:", map( "[$_]", @_[ 1 .. $#_ ] ), "\n" }

x "for",          sub { for( 5 .. 7 ) { 1 } }->();
x "while(5)",     sub { while( 5 ) { 1; last } }->();
x "while(0)",     sub { while( 0 ) { 1 } }->();
x "if(5)",        sub { if( 5 ) { 1 } }->();
x "if(0)",        sub { if( 0 ) { 1 } }->();
x "do{}while(0)", sub { do { 1 } while 0 }->();
x "do{}until(5)", sub { do { 0 } until 5 }->();

__END__
for: [] 
while(5): 
while(0): 
if(5): [1] 
if(0): [0] 
do{}while(0): [1] 
do{}until(5): [0]