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#!/usr/bin/perl -w

...
    'for'   => sub { $_ = 0; for   (;;)  { $_++; last if ($_ == 1000);
+ } },
    'block' => sub { $_ = 0;             { $_++; redo if ($_ < 1000); 
+ } }
});

Benchmark: timing 10000 iterations of block, for, while...
     block:  8 wallclock secs ( 8.13 usr +  0.00 sys =  8.13 CPU)
...
     block: 66 wallclock secs (65.01 usr +  0.00 sys = 65.01 CPU)
       for: 63 wallclock secs (63.18 usr +  0.00 sys = 63.18 CPU)
     while: 64 wallclock secs (64.20 usr +  0.00 sys = 64.20 CPU)