use Acme::Don't;
don't {

# code here
# Note that the code in the don't block must be syntactically
#   valid Perl.
# This is an important feature:
#   you get the accelerated performance of not actually executing
#   the code, without sacrificing the security of compile-time
#   syntax checking.

} while condition();

# And, yes, in strict analogy to the semantics of Perl's magical
#   do...while, the don't...while block is unconditionally not
#   done once before the test. ;-)