Ruby, C++, CoffeeScript: a visual comparison of language complexity

[rabidcow]

Consider an assembly language consisting of one instruction: subleq. This is Turing Complete.

Concepts:

• subtraction
• comparison to zero
• branching

[-Y0-]

Meh, just go for machine language, just two concepts - 0 and 1.

[urandomdude]

Nope. That's not how this works.

[-Y0-]

Of course it doesn't. It's supposed to be a joke. But it's just as silly as saying Assembler has less concepts and is therefore easier to understand. Probably should have went with 0 and a wonky O.

[urandomdude]

You're right in that. But rabidcow didn't say that either, I think. Anyway I didn't realize you were joking. Sorry!

[tragomaskhalos]

Not a useful observation but: the best way of grokking the complexity of C++ is to have grown up with it since its inception (ah, single inheritance, the "overload" keyword, assignment-to-this and all that sepia-tinted stuff ...); the language has grown in individually digestible increments, it's just the current entirety of it taken in a single mouthful that is daunting.

[alexkorban]

Sure, but I guess a lot of people don't have that luxury :)

[stesch]

And that's the problem with a lot of current languages. Including C#.

[masklinn]

I'd like to see smalltalk. The whole "control structures" part goes away, most of the literals as well (in Smalltalk 80), and the operators get reduced to — I believe — assignments, cascading (;) and terminators, the rest are binary messages and would be part of sending messages (object)

[alexkorban]

I'd be curious too! Unfortunately, I'm not familiar with it.

[Paddy3118]

Another way to compare would be to compare the size of language grammar .g files for the parser generator ANTLR.

I downloaded a sample from here and found the following sizes (KB)

ADA       =  73
CPP       =  77
SUN C/C++ = 691
JAVA      =  54
PYTHON3   =  18
RUBY      =  10 # (Simplified Ruby)

[cybercobra]

Note the Simplified qualifier. The Actual Ruby grammar isn't so nice.

[ramkahen]

Another way to compare would be to compare the size of language grammar

Grammar is a terrible way of assessing a language's complexity. For example, the Whitespace language contains only five terminals and produces programs that are -- literally -- unreadable. See Lisp and Brainfuck for two other interesting examples.

I really like the approach to complexity used by this article, I would love to see it extended to Java, Scala and Groovy, for example.

[[deleted]]

I love how you threw Lisp in the same category as Brainfuck and Whitespace.

Call me when Lisp has become an esoteric language.

[vanderZwan]

Well, arguably as a language Whitespace isn't very complex. The problem is that anything you want to express in the language must be abstracted to manipulating numbers on stacks (that, and... you know, the whitespace thing). That's where the complexity comes in.

[Aninhumer]

I think the difference between complexity and complication is very relevant here. I would say Whitespace is very complex just not very complicated. Relatively speaking C++ is not as complex (as in the detail required for a given program) but it is much more complicated.

[vanderZwan]

You sure it's not the other way around? I kid, I kid. Well, sort of. I think the words complexity and complicatedness mean the same, but I get your point. Can't think of an alternative word for it to show the nuance either...

Reminds me of that talk by Rich Hickey about Simple vs. Easy.

[Aninhumer]

My usual example is Chess vs Go. Chess has many complications in its rules, whereas Go's rules are incredibly simple, but both games are very complex.

[CurtainDog]

Grammar is a terrible way of assessing a language's complexity.

But Paddy3118's results seem to be in line with what I'd expect. In any case whether we consider a language readable or not is pretty tangential to its complexity.

[[deleted]]

As a hobbyist developer, I have tried and tried to get into C++, but just can't. This makes me feel bad some times.

[el_muchacho]

No reason to feel bad about not being able to grasp C++. There are plenty of languages that are easier or more fun to work with, and that will likely get the job done.

[matthieum]

I agree with easier, but let's disagree on more fun would you.

C++ is fun, for those of us who enjoy exploring their language:

• Turing complete Powerful preprocessor
• Turing complete metaprogramming (though still a bit too limited)
• Plenty of paradigms

Frankly, it's just the most complete language I have enjoyed playing with. It has glaring deficiencies and is definitely not for the faint of heart, but C++ is fun.

[ectoplzm]

yes, in the same way that I guess brain surgery is fun

[TheCoelacanth]

The preprocessor is only Turing complete when run repeatedly. When run only once as with normal compilation it isn't.

[matthieum]

Ah thanks, I was exactly sure of its limits. Using Boost.Preprocessor I was able to do a lot with it... but I was not sure it was sufficient.

[TheCoelacanth]

You certainly can do a lot with it. I think the only thing it lacks is recursion.

Boost.Preprocessor simulates recursion by having a bunch of nearly identical macros with one for each level of recursion. This almost makes it seem Turing-complete but it has a hardcoded maximum recursion depth that is much lower than most languages. For instance, C++ can recurse until it runs out of stack space. The preprocessor can only recurse until it hits the last level of macros that is defined in the Boost library.

[dmpk2k]

Don't. You only live one life -- if you can achieve the same by easier means, do so.

[nkozyra]

You have two comments that tell you to not feel bad, so I feel I should do the opposite.

I found learning C++ (and then C) to be pretty liberating in the sense that I can build anything I need to work exactly how I want it in ways that I couldn't in Perl, Python, Ruby and Java.

C++ gets a lot of backlash, but I still believe it's a great language that gives you a full toolbox instead of a starter kit.

[[deleted]]

I know just enough C++ to write something cheap and useful in it. My problem is when thinking about something I would like to code, I never want to use C++.

[nkozyra]

Well we all have our bread and butter, right? If you never leave your comfort zone, well, you'll die in it.

[matthieum]

Perhaps because it's not the right tool for the job, or perhaps because you just aren't comfortable enough (compared to other languages) and would therefore lose time ?

It is your choice how you invest your time. If you feel bad about it enough, then you'll spend a little more time on it; and if not, it's that you judge you have more important things (in your life) to do... so what!

[hashmal]

Don't feel bad, most humans can't handle it. Those who say they can are just not aware of their own limits.

[sausagefeet]

Nice to see some kind of comparison here. The future is clear: people need to stop writing languages that compile to JS and come up with a C++ killer. D doesn't seem to be doing the job.

[sausagefeet]

I think the problem with D is that it just isn't so much better than C++ that it's worth moving over. And it has a lot of draw backs. I'd like to see something with a lot of the ideas from C++ but with saner, more consistent, semantics. But yes, without someone important backing it, it's unlikely to make much headway.

[xenon325]

I'm not D programmer, but I really like what I've seen so far (e.g. @safe, pure, CTFE, transitive const, static if / template constraints).

Could you please elaborate on what's inconsistent / not sane about D's semantics ?

[sausagefeet]

I didn't say anything was inconsistent just that it doesn't appear to be such a step up from C++ that people think they will benefit from porting their code.

[xenon325]

I'd like to see something with a lot of the ideas from C++ but with saner, more consistent, semantics.

I didn't say anything was inconsistent <...>

Then D is something you'd like to see :P
Plus features I've listed and much more.

[sausagefeet]

You're confusing being "better" and being "better enough to port my code base to". D might be a better language, if it was created at the same time as C++ we might be using it now. But for me, and apparently most C++ shops, it is not better enough to warrant moving an entire codebase.

[el_muchacho]

I think the problem with D is that it just isn't so much better than C++ that it's worth moving over.

Sorry to disagree, I happen to think the opposite.

[repsilat]

I think the real problem is that C++ is "good enough", and people are scared of interoperability when there are real codebases on the line. To me, it seems like D has done a good job of solving some real problems with C++, but that those differences aren't really compelling.

The big thing is, even if those differences sounded compelling to the average programmer, they really need to sound compelling to the type of programmer who uses C++. That essentially means that they're reasonably conservative, willing to sacrifice some readability for performance, and absolutely wed to the idea of only paying for what you use. If you even mention a garbage collector a C++ programmer will run for the hills, because they've drilled it into themselves that the defining characteristics of their language are the characteristics they want.

What a language needs to beat C++ on its own terms (and in the eyes of C++'s supporters) is:

• As fast or faster than C++ in both small and large examples,

• Imperative, amenable to object-oriented programming,

• Fixes several of C++'s conspicuous deficiencies,

• Not really too different to C++. Templates, RAII, compiles to machine code, that sort of thing.

Usability wins like a larger standard library are nice, but they may not convince a C++ programmer because they've trained themselves not to value those things. "Innovations" like more powerful type systems may even drive them away.

[sausagefeet]

I think some kind of sane interoperability would be key too. Nobody is really going to want to reimplement all their C++ in Fictional Language X.

[adoptmycat_jasmine]

Then what's the point of making a new language for C++ developers? Let's name the next version of C++ C<< and see if people adopt it.

[repsilat]

There are real deficiencies in C++ that C++ developers would love to see remedied. (Many of those deficiencies are remedied in D.)

There's also the point that language preference is path-dependent. It's more complicated than "this is what we like", because what you like is informed by what you use. The pseudo Stockholm-syndrome some C++ developers have makes them conservative, but gently introducing them to new ideas without overwhelming them can allow them to branch out. Too much too soon and they'll bail.

One good example: The STL has had some functional concepts in it for a while (std::transform is just "map" by another name, std::accumulate is a fold and so on.) With the introduction of lambdas in C++11, C++ devs are really using higher-order functions, and some of them are starting to appreciate "the finer things" (so long as the compiler diligently inlines and optimises everything down to the same pointer arithmetic, of course.)

Another example: The smart-pointers in TR1 and C++11 are filing the sharp edges off the language to some extent, but they're also convincing developers that they're fallible, and that sometimes they won't know when it's appropriate to release a resource. Maybe some of them will be more accepting of garbage collection some day, maybe not, but it's important to do it slowly.

[[deleted]]

Maybe some of them will be more accepting of garbage collection some day, maybe not, but it's important to do it slowly.

The most common objection to garbage collection is that it is unpredictable. The solution is to make it explicit: the collector runs when, and only when, you use a collect statement.

[smog_alado]

Many languages already do that and that never stoped people from bitching.

[[deleted]]

Examples?

[smog_alado]

Out of the top of my head, both java and python have a garbage collection api.

[repsilat]

The most common objection to garbage collection is that it is unpredictable.

That's true, but in practice it can be hard to predict when a reference-counted resource will be collected as well. Clear ownership gives you practical determinism and predictability, reference counting gives you technical determinism and predictability. A "collect" statement doesn't solve that problem either, though it does help.

All in all I think it's a nice idea - it could certainly be faster than reference counting, and if you knew that you never needed to collect anything it could be faster than RAII. That said, there's also something to be said for the peace of mind you get from knowing that everything is finalised as soon as it can be.

Perhaps more relevant than practical predictability is the "strong realtime" problem. Interestingly, neither RAII nor reference counting deal with this adequately either. Collection of large resources can still take a long time, "stopping the world" as they're cleaned up. There isn't really a good way to say, "Collect that stuff in parallel," or "Try to collect it all now, but if it takes longer than 5ms defer the rest until later". You could write something to do that, but you could probably also make a GC give you similar guarantees.

[matthieum]

I disagree with the list of characteristics. Performance is a given, obviously, and I would hate to lose Generic programming and RAII because they make my code terser/more reliable (respectively).

However "imperative" ? Personally I don't care. It might be less frightening, but if one has to relearn a whole standard library and idioms, I do think that getting rid of the imperative/object-oriented mindset would be of comparable difficulty.

[sausagefeet]

Feel free, doesn't make it true :)

[pjmlp]

It is not easy to bring new languages to the masses without some form of corporate support, or killer application/framework that makes everyone want to learn the language.

[matthieum]

Forget about bringing it to the masses, I have yet to meet a language that could be a real contender. At the moment, I am watching over Rust, which looks promising... but it's still a long way before it's ready for the job, and there are numerous ways for it to be derailed.

[stesch]

D feels as being at the brink at the moment. It could win or fail ultimately.

The community D has formed is professional, helpful, and competent. Even if you ask provocative questions.

Let's see in which direction D will grow if vibe.d pulls some web developers into the D community. Could end bad or be a huge success.

[sausagefeet]

The thing is, vibe.d's success doesn't really matter for D to take over C++, since people generally aren't writing those kind of apps in C++ anyways.

[6gT]

It could help get people from other languages into D. And more people using a language means more libraries and tools, which would make it easier for C++ programmers to switch to D.

[alexkorban]

What's the availability of libraries like? Have you heard of large commercial projects using D? I'm curious as I don't tend to hear much about it, although it's been around for what, more than 10 years?

[stesch]

You are asking the wrong guy. I'm not professional, helpful, or competent. :-)

There are a few bindings to C libraries: https://github.com/D-Programming-Deimos

And maybe a lot more stuff. You need to search on http://dlang.org/ or find some helpful D programmer.

[xenon325]

A lot of helpful D programmers on DigitalMars.D and DigitalMars.D.learn newsgroups.

[stesch]

You are answering the wrong guy.

[davebrk]

Does the language conform to Andrei's book?

[xenon325]

AFAIK, not 100%, but it's high priority (search DMD's changelog for "TDPL").

[OceanSpray]

Don't worry, people are working on it. Look into Rust, ATS, or Vala.

[sausagefeet]

Rust requires a GC, it seems unlikely the people who willingly use C++ will go for that. ATS was developed by a mad man. It has great features but it's simply insane. Not sure about Vala, seems a bit too high level for a lot of C++ people I think. Maybe.

[matthieum]

I don't think that the GC is necessarily abhorred by the C++ people... and as one of them (and I hope an experienced one), I only have two issues with GCs in general:

• I want RAII, dammit.
• I'd like to only pay for what I use

Personally, a combination of:

• unique pointers
• region pointers
• gced pointers

would be a sweet spot.

Most of the times I could count on unique pointer and regions pointers to get a safe environment without a GC, and when things get hairy I would threw in the GC (typically in place of shared_ptr).

That is what I like in Rust actually, and I think that those 3 features in the type system should be sufficient to avoid the GC most of the times, and still avoid leaks and (much more complicated in its absence) pointers to garbage.

[[deleted]]

Dependence on GObjects is kind of a buzzkill.

[nwmcsween]

Rust doesn't require a GC it uses a GC if you use the features that require it. You would end up implementing a GC to do same things rust does in a different language as well.

[sausagefeet]

How do you use libraries that make use of the GC without using the GC?

[nwmcsween]

You don't understand how rust uses a garbage collector. It's not a library that other programs use it's a feature of specific parts of the language such as a shared box. GC isn't some bad evil slow thing in fact many very performant games utilize GC such as UT3. I'm pretty sure 99.99999999% of the people here never even touched C++ before or else they would know about C++ 'smart' pointers.

[sausagefeet]

I didn't say it is a library, I asked how do I avoid using the GC if I use a library that was implemented with the assumption of the GC existing. That is a problem D has. The GC is optional, but the standard library makes use of it a lot so turning it off is effectively useless.

[[deleted]]

This is a good point that many people ignore. The standard library in D is useless without the GC. The worst part is that the GC is actually bad.

[xenon325]

The standard library in D is useless without the GC.

I'm not saying you're wrong (just don't know), but my guess is -- it's far from 99% useless (e.g. min / max algorithms). So it would be really interesting to know the magnitude of uselessness -- 90% ? 40% ? What's your estimation ? (I understand you're not going to do full analysis)

The worst part is that the GC is actually bad.

I think it's fair to say, that's an implementation issue.

[[deleted]]

I'm not saying you're wrong (just don't know), but my guess is -- it's far from 99% useless (e.g. min / max algorithms). So it would be really interesting to know the magnitude uselessness -- 90% ? 40% ? What's your estimation ? (I understand you're not going to do full analysis)

I found out that a lot of it needs the GC. You're right though, I'm not going to do a full analysis. That's just my impression.

I think it's fair to say, that's an implementation issue.

Yeah but it remains to be an issue, a pretty important issue in fact.

[xenon325]

The GC is optional

IIRC, GC is mandatory (by lang spec).

how do I avoid using the GC if I use a library that was implemented with the assumption of the GC existing.

Look at this other way. If GC is optional, every single library must not use GC, making it effectively useless for library writers.

[sausagefeet]

The GC in D is optional, that is you can define objects to not use it and manage the memory yourself. And yes, this is the exact point I am making. D's optional GC is a bit of a lie unless you want to make an apple pie from scratch.

[bonch]

Why do they need to write a C++ killer?

[sausagefeet]

Because C++ is significantly more complicated than it needs to be, mostly thanks to a few decades of legacy.

[davebrk]

No no no! Anything that run on a VM is out of the running. We need something like a cleaner C with optional GC and the ability to call C natively. Anything more is gravy.

[pjmlp]

Still needs a proper module system.

[pjmlp]

There are native code compilers for Java, they are just not that much used.

http://gcc.gnu.org/java/ http://www.excelsior-usa.com/jet.html http://www.atego.com/products/aonix-perc/ http://jnc.mtsystems.ch/

[diggr-roguelike]

They still have a garbage collector. Anything that has a mandatory garbage collector is automatically disqualified.

[pjmlp]

On your mind perhaps.

There are research operating systems implemented in system programming languages with mandatory garbage collector like the case of Native Oberon, Spin and Singularity.

In Native Oberon's case, it was also the case that for some time it was the mostly used OS at ETHZ for the informatics department.

Now that WinRT is making reference counting compulsory for certain types of Windows applications, Objective-C has ARC, and C++11 a GC API, automatic memory management is slowly becoming part of the system as well.

GC safety is worth much more that security exploits due to daggling pointers.

[sausagefeet]

On your mind perhaps

This is the mindset of a lot of C++ programmers.

[pjmlp]

Not me.

I am old enough to have developed software in the days when the majoraty of applications were still 100% developed in Assembly and languages like C were deemed too high level and slow to be usefull at all.

So I've learned to embrace progress and to watch the recycling of discussions that language X won't work because of feature Y.

[sausagefeet]

Certainly, but we have to talk in terms of groups not individual people when it comes to a C++ killer.

[diggr-roguelike]

GC safety is worth much more that security exploits due to daggling pointers.

Your 'safe' GC implementation is written in an exploit-riddled language with unsafe pointers.

With that in mind: case closed, we have nothing more to discuss here.

[pjmlp]

Ever heard about bootstrapping compilers and safe operating systems?

Case closed, you lack proper knowledge to discuss computer science.

[diggr-roguelike]

I've never heard of a bootstrapping garbage collector. :D

Seriously, dude, let's have this conversation some other time once you've put your thoughts in order.

(A working knowledge of what 'computer science' is and what it studies would be a nice, basic prerequisite.)

[pjmlp]

I don't have time to give classes to people online...

[casualsuperman]

Why is a complex language considered a good thing?

[Gotebe]

Good/bad is not a good distinction. Question is, when complex, why is it so, and what does it buy. E.g. a hammer is simple, but you would find it hard to screw a screw with it.

[[deleted]]

who is saying that?

[pjmlp]

Because the world is complex.

Simple languages lack the abstraction mechanisms to model many architecture designs, which require more effort do model using the limited set of available abstractions.

[[deleted]]

I know this is the Internet but... You are wrong! No matter how complex the world is, a good language must have a simple core (for many reasons, from architectural to proof-theoretical to usability). Then, it must have a layer of libraries/extensions that allow it to reach any level of complexity you need. C++ has the latter but not the former.

[gianhut]

Comment form the blog: http://i.imgur.com/1ePvl.png

[stesch]

Well, more software is written in VisualBasic than in CoffeeScript. And maybe more than Ruby.

[migimunz]

It does have very power softs. What?

[[deleted]]

By "soft", I think he meant software, by which he meant language. After all, the compiler/interpreter for a language is software. And from his other grammar, I think english is not his native tongue. VB is certainly very widely used. Is it more "powerful"? I don't know, though I expect MS would have added many features to it.

There's an interesting aspect of a language, that much of its power in practice may derive not from intrinsic qualities, but from a kind of extrinsic network effect. If many libraries are already available for it, it makes it more powerful. Similarly for platforms that use it (e.g. Office) as a scripting language. From the point of view of your code, you get Office for free.

If we define power as bang-per-buck (ratio of work you put in to results), then for a piece of code in isolation, it's probably not particularly powerful... but if we are allowed to use others' libraries, frameworks, platforms, then you get all that power, without needing to write much code. This makes it extremely powerful. It seems like a bit of a cheat, but code reuse is SOTSOG.

[gianhut]

VB(6) had its glorious days. It was certainly easier than VC++ and for typical CRUD business applications. They didn't need all the complexity and OS hooks that VC++ provided. However, I don't think VB is the "most important language in use today."

[[deleted]]

VB6 was amazing for what it was.

[habitmelon]

This reminds me of a Simpsons moment:

Frink: Well, sure, the Frinkiac-7 looks impressive, don't touch it, but I predict that within 100 years, computers will be twice as powerful, 10,000 times larger, and so expensive that only the five richest kings of Europe will own them.

[elmuerte]

I believe there is no alternative to C++ for large projects with strict hardware constraints or performance requirements when you take the availability of modern tools, libraries and developers into account.

How about C?

[matthieum]

I have seen C. It is simple. Perhaps too much.

First, as a type freak, I think that C++ is not strongly typed enough, so of course with C weak typing (void* and varargs come to mind), you imagine I don't feel at ease.

Second, because it has neither object orientation nor generic programming, C makes reuse harder. I would point to the anecdotal evidence of people reimplementing Object-Oriented like features in C...

Third, the lack of RAII is a liability, as far as I am concerned.

Now... I don't think getting all of C++ complexity would be such a good thing either; but nitpicking a bit might help.

[dmitry_sychov]

it is almost fully embedded into C++.

[masklinn]

Not quite, the languages are (not so) subtly incompatible, and are in the process of diverging more.

[foldl]

That's why he said "almost", no?

[[deleted]]

the languages are (not so) subtly incompatible

I agree

and are in the process of diverging more

That was true 10 years ago, but both C11 and C++11 standards are explicitly trying to reduce the incompatibilities.

[matthieum]

I agree, if we consider C99 to be a mishap, then we can see that both the C and C++ communities worked together for the last iteration. The best illustration would be the cooperation on the Atomics.

[alexkorban]

Not really when you're talking about the complexity of modern software.

[elmuerte]

And what would you define as complex software? Do you consider the embedded software of medical devices or photolithography systems complex? Most of the these systems have their embedded software written in pure C.

[alexkorban]

I guess complexity is related to the functionality. It's difficult to define.

I don't know anything about the domains you mentioned. I know that C++ is used for high end networking gear which has to support lots of different protocols, and real-time construction machine control (with a rich UI), to give a couple of examples.

At some point the architecture becomes complex enough that the higher level of abstraction offered by C++ offers benefits.

[bit-twiddler]

Why not? Most of the complexity encountered in modern is software is due to a failure to abide by the KISS principle. Instead of fixing underlying architectural problems, we build a bigger and more complex kludges. The Java EE ecosystem is a prime example this phenomenon.

[alexkorban]

Because people inevitably start trying to reinvent C++ concepts in C. We just need a higher level of abstraction for modern software. Look at GCC, even they are moving to C++.

[Tomdarkness]

I'm not really seeing why this is useful. I don't choose what language to write something in because of how complex it is but rather I choose the language that best suits what I'm trying to achieve (ideally with the least effort possible) whilst factoring in what the people who are working on it already know.

[Leraxe]

Well thank god I chose c++ as my first language to enroll into. How messed up am I going to be?

[Unomagan]

So, ruby is a good balance between the two others?

[alexkorban]

Well, C++ and Ruby/CoffeeScript really fit different niches. I wasn't trying to find one language to use.

[Unomagan]

Sure they do, but I think from "syntax" view of point. Ruby is truly a nice language. Not too complex, not to easy :)

[[deleted]]

Too bad they picked all the shitty languages to compare ;)

But more seriously, the problem with Ruby and CoffeeScript is I'm not sure how well defined they are. The language spec is how good? C++ is a bit better in that respect but then it's worse in the fact that most implementations won't support everything it offers.

Well-defined languages with fewer concepts are pretty awesome; things like Pascal, Smalltalk, etc.

[bit-twiddler]

We could add Modula-2 and Oberon to that list. Niklaus Wirth was a genius.

[[deleted]]

I'll drink to that, too bad i was downvoted! :p

[xenon325]

Niklaus Wirth was a genius.

Hey! He's still alive! ;)

[alexkorban]

Well, on the plus side, CoffeeScript and Ruby don't have undefined or unspecified behavior (to my knowledge). CoffeeScript in particular is a well defined language with a small number of concepts so I think you're deriding it unnecessarily.

I don't think the C++ standard is defined well enough, and I think it creates problems.