#Want to sort a complex data structure by some element
#efficiently?  For example, how do you sort an array
#of strings by their length?  Use the transform:
   @sorted = map { $_->[1] }
   sort { $a->[0] <=> $b->[0] }
   map { [ length $_, $_ ] } @strings;

#Confused?  Put in temporary arrays, 
#just to see what we're doing.

# create a temporary array of anonymous arrays
# (0: length of the string, 1: the string)
   @temp = map { [ length $_, $_ ] } @strings;
# sort by length
   @temp = sort { $a->[0] <=> $b->[0] };
# grab just the strings and put them in @ordered
   @sorted = map { $_->[1] } @temp;

#Knowing the context of certain operations
# and being able to chain them together
# is crucial to a deep and idiomatic
# understanding of Perl.