[yohanatan]

Are you sure about that? Given that any [Turing-complete] language feature can be implemented in any other [Turing-complete] language, the only conceivable difference is in fact length of implementation.

In other words, it is possible to express anything in one Turing-complete language that is possible to express in another.

[hetman]

Except my brain isn't a Turing machine. What expressiveness means then is how easily I can fit the concepts of the code in my head (not on my harddrive). This is not the same as how short the code is, though the two are often closely related.

[yohanatan]

Expressiveness is power and it applies to the act of writing code, not reading it. I agree that it is ideal if one's code can be read and comprehended easily by others although that has little to do with expressiveness.

http://www.paulgraham.com/power.html

[cgag]

To me, expressiveness is about expressing an idea with as little incidental complexity as possible, which is definitely different from as in as few characters as possible.

[yohanatan]

I don't think it is different actually. 'Kolmogorov complexity' (which is essentially the global minimum 'essential complexity' of a particular algorithm) is specified in terms of length.

[fauigerzigerk]

Applying Kolmogorov complexity in this context is a bit more tricky than you make it appear. Kolmogorov complexity measures the complexity of a string as the length of the shortest possible program that generates that string.

So to measure the complexity of a program P we have to write another program G that generates P and then take G's length. It's not a given that a generator for a verbose language is necessarily longer than a generator for a terse language.

But more importantly, what we want to measure is the mental effort required to write and understand code in different languages. To measure that effort in terms of Kolmogorov complexity, we'd have to write a program that generates our states of mind while programming.

Good luck with that ;-)

[yohanatan]

Actually, given a Turing Machine M which outputs x when given x, then we would have the description of program T0 (for terse language T) equal to the concatenation of the [specification of the] machine M with T0, M T0. Given program J1 (for verbose language J), its description equals M J1. Given sufficiently small M and large T0, the M factor's importance is quite reduced and we see that Kolmogorov complexity is roughly analogous to the respective sizes of T0 and J1 themselves (for this specific Turing Machine M).

[fauigerzigerk]

You're forgetting that Kolmogorov complexity is the shortest possible description, not just any description of the desired output. The concatenation you're suggesting is highly unlikely to be the shortest possible one.

You have to think of it in terms of compression, because that's what Kolmogorov complexity is really about. It is certainly possible that after compression J1 is shorter than T0.

[yohanatan]

You're forgetting that I get to pick the Turing machine to use. Kolmogorov complexity is the shortest possible description relative to a particular Turing machine. Re-read my previous post with that in mind.

[kvb]

See Felleisen's "On the Expressive Power of Programming Languages"[1] for one formalization that differs from conciseness. Essentially, Turing complete languages can express the same programs at the very coarse "whole program" level, but the paper advocates taking a more local view to assess expressiveness (e.g. what programs in L1 can you write in L2 without having to do a whole program transformation). See also Neal Gafter's related commentary[2] (in the context of the various proposals for closures in Java).

[1] http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.51.4...

[2] http://gafter.blogspot.com/2007/03/on-expressive-power-of-pr...

[yohanatan]

One doesn't have to look far before he finds a fatal flaw in the commentary. Particularly this:

"In my mind, a language construct is expressive if it enables you to write (and use) an API that can't be written (and used) without the construct." - Neil Gafter

Once more, there is no such construct. All APIs can be written and consumed without language support. Otherwise, Boost would not have had all the new C++ goodies (as an add-on library) before they became part of the language itself. And, of course, one can always put the 'human compiler' to work to produce boilerplate that would be produced by the compiler if the language in question supported the feature in question (if there isn't an add-on library providing the feature in question). One can always do this but the discriminating one tries to avoid it and instead chooses 'expressive' (i.e., conciseness-facilitating) languages. [In the case of closures in Java, one [human-compiler] would merely use one-off interfaces or anonymous classes].

I will take a look at the other links but I gave up on the commentary after seeing such a blatant falsehood.

[kvb]

C++ has features like operator overloading that make faking lambdas via Boost feasible. And even Java has anonymous inner classes that allow a rather ugly local transformation somewhat akin to closures. But if you removed that feature, then you'd need a non-local transformation to fake them.

[yohanatan]

You apparently didn't read all of my comment as I mentioned Java's anonymous inner classes being used to fake lambdas near the end. And, the point remains, given any TC language L, all possible language features for all possible languages are implementable within L itself. It doesn't matter if L has operator overloading or not; only that it be TC.

[cmccabe]

Are you sure about that?

Yes.

[yohanatan]

You can be sure if you want but unless you back up your claim with some reasoning, others will consider you wrong.

[CCs]

A line from a real code (a library):

    "* ^^"._? #> (a.!?(1, Get())) must be_==(Full(Answer(1))) ?~! eventually

It is very short, most of the people would implement the same thing using 5-10 lines of code. I prefer 5-10 lines of code over regex-like syntax.

[cmccabe]

A more obvious example is minified JS versus regular JS. Briefer? Definitely. More expressive? Definitely not.

[cmccabe]

"Brevity and expressiveness are not the same."

"Are you sure about that?"

"Yes."

Do I need to explain?

[yohanatan]

I think you're confusing expressiveness of the language with expressiveness of a particular text written in that language. English certainly affords you the opportunity to share more thoughts but given that you seemingly only wanted to express an affirmative, in English 'yes' is pretty much the minimum. You could have said 'Ya' but that is slang. If you open up the choice of language then you could have said 'si', or '#t' or even just '1'. But with such a short intended message, language choice hardly matters.

Certainly if you intended to say more than 'yes' then you failed at adequately expressing the message to begin with so comparisons at that point are moot: i.e., two pieces of text must both express precisely the same ideas before comparisons of them make sense.

[charlieflowers]

He gets points for brevity. You gotta admit that :)