[OFFTOPIC] Re: Appending lists

[Stefan Monnier]

>>>> Just to show that you should never say never:
>>> Hey, that's cheating :-)
>> Impredicativity is borderline, indeed.
> Impredicativity, what's that, recursion?

(with-lecture-mode

Kind of, except the cycle is not "definition refers to itself" (the
"traditional" form of recursion) but rather "definition can be applied
to itself" as in the first sentence quoted above ;-)

These forms of circularity have been a great source of hilarity for
logicians and philosophers over the years, but more relevantly for
programmers they've been the source of the invention of the notion of
"type", introduced by Bertrand Russel about a century ago to try and
rule out those forms of circularity by stratifying logical
statements.                                                        )


        Stefan