Lambda: the Ultimate Design Flaw

[Daniel Silva]

Shriram Krishnamurthi has just announced the following elsewhere; it might
be of interest to c.l.s, c.l.f, and c.l.p:
http://list.cs.brown.edu/pipermail/p...il/008382.html
The Fate Of LAMBDA in PLT Scheme v300
or
Lambda the Ultimate Design Flaw

About 30 years ago, Scheme had FILTER and MAP courtesy of Lisp hackers
who missed them from their past experience. To this collection,
Scheme added a lexically-scoped, properly-functioning LAMBDA. But,
despite of the PR value of anything with Guy Steele's name associated
with it, we think these features should be cut from PLT Scheme v300.

We think dropping FILTER and MAP is pretty uncontroversial ; (filter P
S) is almost always written clearer as a DO loop (plus the LAMBDA is
slower than the loop). Even more so for (map F S). In all cases,
writing the equivalent imperative program is clearly beneficial.

Why drop LAMBDA? Most Scheme users are unfamiliar with Alonzo Church
(indeed, they don't even know that he was related to Guy Steele), so
the name is confusing; also, there is a widespread misunderstandin g
that LAMBDA can do things that a nested function can't -- we still
recall Dan Friedman's Aha! after we showed him that there was no
difference! (However, he appears to have since lapsed in his ways.)
Even with a better name, we think having the two choices side-by-side
just requires programmers to think about their program; not having the
choice streamlines the thought process, and Scheme is designed from
the ground up to, as much as possible, keep programmers from thinking
at all.

So now FOLD. This is actually the one we've always hated most,
because, apart from a few examples involving + or *, almost every time
we see a FOLD call with a non-trivial function argument, we have to
grab pen and paper and imagine the *result* of a function flowing back
in as the *argument* to a function. Plus, there are *more* arguments
coming in on the side! This is all absurdly complicated. Because
almost all the examples of FOLD we found in practice could be written
as a simple loop with an accumulator, this style should be preferred,
perhaps with us providing a simple helper function to abstract away
the boilerplate code. At any rate, FOLD must fold.

--The PLT Scheme Team

[Sunnan]

Ville Vainio wrote:

Boring code is code that numbs your senses with constant flow of
boilerplate crap, memory management and redundant type declarations
and general blah blah that you skip when you are trying to figure out
what a piece of code does.
The python code I've read so far has looked like that. Not type
declarations, but loooong class declarations.

Also, Guido recently urged people to explicitly write recursions rather
than to use reduce - which I thought was completely in line with what
I've seen as python's goals: readability/understandabili ty as more
important than terseness/non-boringness.
It's a code that you wish you could train a
monkey to write for you while you go for lunch. Think C++ or Java.

Oh, yes. C++ and Java can be super boring. C++ can also be pretty hard
to understand - it's not all boilerplate.

I'm not saying Python is always boring (maybe I've just been in an
easily bored mood when I've read Python stuff), and I'm not saying that
boring is always bad.

Yesterday, I read some marketing prop describing a proprietary IDE
(don't remember what language) as "exciting", and I went "Ugh, no
thanks! Give me calm computing." And then I thought - wait: I just
ranted about boringness on comp.lang.pytho n. Can't boring and calm
sometimes mean the same thing?

[Ville Vainio]

>>>>> "Sunnan" == Sunnan <su****@handgra nat.org> writes:

Sunnan> Ville Vainio wrote:

Sunnan> Also, Guido recently urged people to explicitly write
Sunnan> recursions rather than to use reduce - which I thought was
Sunnan> completely in line with what I've seen as python's goals:
Sunnan> readability/understandabili ty as more important than
Sunnan> terseness/non-boringness.

The problem w/ reduce is that it's not intuitive. You'll have to stop
to think what the code w/ reduce does - effectively converting it to a
normal loop (not recursion!) in your head. It's a net loss when you
compare it to just reading an explicit loop as written in code.

Sunnan> Yesterday, I read some marketing prop describing a
Sunnan> proprietary IDE (don't remember what language) as
Sunnan> "exciting", and I went "Ugh, no thanks! Give me calm
Sunnan> computing." And then I thought - wait: I just ranted about
Sunnan> boringness on comp.lang.pytho n. Can't boring and calm
Sunnan> sometimes mean the same thing?

Not for me at least. 'Boring' implies a certain sense of frustration,
not getting anywhere and generally feeling like you are wasting your
time. Human attention is a limited resource, and being bored leads to
loss of attention.

--
Ville Vainio http://tinyurl.com/2prnb

[Michele Simionato]

Sunnan:

The python code I've read so far has looked like that. Not > type

declarations, but loooong class declarations.

What do you mean? Lots of repetitive
"self.variable= variable" in the __init__ method? Use of classes when
you would use closures? Or maybe you
are comparing with CLOS classes, which are pretty
slim, since the (multi)methods are defined outside
them?

Michele Simionato

[François Pinard]

[Aahz]

[François]

Many of us are using Python today, week after week, year long. So
let's be pragmatic. Python is what it became and now is. Let's not
define it as a memory from the past nor as a futuristic dream.

You're free to continue using 1.5.2. [...]

Sure, of course. Yet, our friendly argument is sliding away from was it
originally was. The point was about not asserting in this forum that
Python "has only one way to do it", because this is not true anymore.

The principle has been, it may be back in some distant future, but now
it is not.

--
François Pinard http://pinard.progiciels-bpi.ca

[Scott David Daniels]

Aahz wrote:

You just can't have your cake and eat it, too.

I've always wondered about this turn of phrase. I seldom
eat a cake at one sitting.

-Scott David Daniels
Sc***********@A cm.Org

[Simon Brunning]

On Apr 6, 2005 4:42 PM, Scott David Daniels <Sc***********@ acm.org> wrote:

I've always wondered about this turn of phrase. I seldom
eat a cake at one sitting.

Clearly you're just not trying. ;-)

--
Cheers,
Simon B,
si***@brunningo nline.net,
http://www.brunningonline.net/simon/blog/

[bruno modulix]

Sunnan wrote:

Aahz wrote:

(snip)

print "foo is", foo

Is the space added automatically? (Like awk does, if you add a comma.)

Yes. But you can also format it how you like:
print "foo is %s and that's a good news, my friends" % foo

--
bruno desthuilliers
python -c "print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in 'o****@xiludom. gro'.split('@')])"

[John J. Lee]

Simon Brunning <si************ @gmail.com> writes:

On Apr 6, 2005 4:42 PM, Scott David Daniels <Sc***********@ acm.org> wrote:

I've always wondered about this turn of phrase. I seldom
eat a cake at one sitting.

Clearly you're just not trying. ;-)

:-)))
John