take advantage of the fact that the ternary operator has a return value

How true; Perl is a bit unorthogonal in this respect, in that there is (at least) one case where you can achieve this effect with a plain 'if':

sub lessthan {
  if($_[0] < $_[1]) {1} else {0}
}
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Some languages (old examples: Algol60 and Algol68) are more regular in this respect...

BTW, does someone know by chance which was the first language which used ?: to represent "ternary if"? Of course you had this already in LISP or BCPL, but with a different syntax. The earliest occurance of ?: I know of, is in C, but I wouldn't be surprised if it was used in even older languages already.