checking if a list is empty

[rusi]

Mathematics has existed for millenia.
Hindu-arabic numerals (base-10 numbers) have been known for about one
millennium
The boolean domain is only a 100 years old.
Unsurprisingly it is not quite 'first-class' yet: See
http://www.cs.utexas.edu/users/EWD/transcriptions/EWD10xx/EWD1070.html
[Lifted from http://c2.com/cgi/wiki?EqualVsTrueFalse ]

----------------------------
"In retrospect, one might be tempted to regard the introduction of
something as simple as the boolean domain as a minor invention, but I
think that that would be a grave mistake: it is a great invention
because, being so simple, it is such a powerful simplifier. It is of
the same level as the introduction of natural numbers, which enabled
us to add 3 to 5, regardless of whether we are adding apples or
pears."

"George Boole made a radical invention, so radical, in fact, that now,
more than a century later, the scientific community has not absorbed
it yet. (To stay with the metaphor: officially, boolean expressions
may have reached the status of first-class citizens, in practice —
because old habits and prejudices die hard— they are still the victims
of discrimination.) Let me give you a few examples."

"In the programming language FORTRAN, as conceived a century after
Boole published his invention, boolean expressions are allowed, but
there are no boolean variables! Their introduction into programming
had to wait until the design of ALGOL 60."

------------------------
So, M Harris problem is that python could almost be a language for the
'masses' (whatever that might mean) were it not for warts like "l not
is empty" is shorten-able to just "l"

Dijkstra's problem (paraphrased) is that python, by choosing the
FORTRAN alternative of having a non-first-class boolean type, hinders
scientific/mathematical thinking/progress.

I tend to agree with Dijkstra's view that the boolean type should be
given more respect
except for the small fact that the computer's ALU is based on the
logic-arithmetic pun:
half-adder = xor
(half)-carry = and