For what it's worth, a few minor errata that caught my eye:

• Page 100, last non-code line: this line references "even()" but all of the earlier mentions said "odd()".
• Pge 308, first non-code line: "table-drive approach" =~ s/ve /ven /;

I can't find the Getopt::Clade on CPAN; am I looking in the wrong place?

Also, on page 151-152, I was disapointed not to find an example of GRT sorting; I know you mention it on page 164, but a roll-your-own example might help popularize this seemingly esoteric technique...

# Sort by SHA-512 digest of scripts
# (optimized with Gutman-Rosler packed default sort)
@sorted_scripts 
  = map { substr($_, 64) } 
    sort 
    map { sha512($_) . $_ } 
      @scripts;
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