<b_jonas> learn ayacc is ais523\'s yacc parser generator implementation, get it from (darcs clone http://nethack4.org/projects/ayacc) or a snapshot from "http://nethack4.org/pastebin/ayacc-2020-04.tar.gz".

#!/usr/bin/perl
$c=unpack"C",$ARGV[0];print+($c&1?"H":"h"),"ello",($c&2?"":","),($c&4?" W":" w"),"orld",($c&16?$c&8?",":"!":$c&8?".":""),($c&32?"":"\n");