What next generation low level language is the best bet when migrating a code base?

Let's say you have a company running a lot of C/C++, and you want to start planning migration to new technologies so you don't end up like COBOL companies 15 years ago.

For now, C/C++ runs more than fine and there is plenty dev on the market for it.

But you want to start thinking about it now, because given the huge running code base and the data sensitivity, you feel it can take 5-10 years to move to the next step without overloading the budget and the dev teams.

You have heard about D, starting to be quite mature, and Go, promising to be quite popular.

What would be your choice and why?

D and Go will probably just become as popular as Python and Ruby are today. They each fill a niche, and even though D was supposed to be a full-fledged replacement of C++, it probably will never acquire enough mass to push C++ away. Not to mention that they both aren't stable/mature enough, and it's unknown whether you'll have support for these languages in 10-20 years for the then-current hardware and operating systems. Considering that C/C++ is pretty much the compiled language and is used in the great majority of operating systems and native-code applications, it's very unlikely that it'll go away in the foreseeable future.

C and C++ are a pretty much unbeatable combo when it comes to native/unmanaged/"lowlevel" languages.

Not because they're the best languages, far from it, but because they're there, they do the job, and they're good enough. There's little doubt that D, for example, is better than C++ in most respects. But it fails in the most important one: Compatibility with all the existing C++ code. Without that requirement, most of that code would be written in a managed language today anyway. The only reason so many codebases use C++ today is because they used it last year, and it'd be too much of a pain to switch to something else. But if and when they switch, they typically don't switch to D. They switch to C# or Java or Python.

The problem for D and other "upcoming" languages competing for the same niches, is that while they're better, they're not groundbreaking enough to motivate people to actually switch to them.

So C and C++ are here to stay. C is unlikely to evolve much further. It is as it is, and one of the niches it has to fill is "simplicity, even for compiler writers". No other language is likely to beat it in that niche, even if they never revise the standard again.

C++ is evolving much more dramatically, with C++0x getting nearer, and they've already got a huge list of features they want to do afterwards. C++ isn't a dead end in any way.

Both languages are here to stay. Perhaps in 50 years other languages will have replaced them, but it won't happen this decade.

I currently use D regularly. I wouldn't recommend it yet for people writing production code because it's too bleeding edge. I get away with it because most of my code is research prototypes in bioinformatics. However, the language is starting to stabilize. Andrei Alexandrescu is releasing a book titled "The D Programming Language" next March, and right now there is a push to stabilize the spec for version 2 of the language in time for the book.

While D is not a formal superset of C, it is what I'd call an idiomatic superset except for the lack of a preprocessor. In other words, any code written in C proper (ignoring the preprocessor), can be trivially translated to D without a redesign, because C concepts like pointers and inline ASM are there and work the same in D as in C. D also supports direct linking to C code and the D standard library includes the entire C standard library.

Also, despite D's lack of libraries because it is still a bleeding edge language, it's a library writer's dream because of its metaprogramming capabilities. If it takes off, it will probably have some pretty impressive libs. For a preview of this, see std.range or std.algorithm in the D2 standard library (Phobos). As another example, I implemented an OpenMP-like parallelism model (parallel foreach, parallel map, parallel reduce, futures) as a pure library in D, without any special compiler support. (See http://cis.jhu.edu/~dsimcha/parallelFuture.html)

Given that you're mostly interested in the long term, I'd say give D 6 months to stabilize (given Andrei's book and the current push to stabilize the language, version 2 should be stable by then) and then take a hard look at it.

Edit: Now that the core language spec is relatively stable and the focus has turned to toolchain and library development, I would recommend D for small production projects unless you are in a very risk-averse environment. Larger projects that absolutely must have good toolchain and library support should still wait, though.

If you believe in the lean manufacturing principles, you should strive to "decide as late as possible". The moment should be the last responsible moment, meaning the moment at which failing to make a decision eliminates an important alternative.

I think this principle can be applied to your situation. Instead of committing now to a language (that you don't even know will be around in 10 years), you should keep your options open. Maybe refactor some of your code so it is a bit more generic or is built on more abstractions, so that when it is indeed required to migrate, the process will be easier.

Stick with C and C++. I don't see it going the way of COBOL, it runs as well as anything, and you'll have no problem finding people to code in C and C++.

C++ -- it is relatively young and updated... It has a big number of compiler vendors and got
improved all the time.

C -- it would live for a long time filling the gap between assembler and higher level languages. It is also very simple and easy to implement language, so it would remain the
first language for various "strange" architectures like embedded or extremely new ones.

D is promising but still very new and unstable specifications and libraries.

Go was born few weeks ago... Never use anything of version 0 for big important projects. Also it is significantly more limited the C++ or D.

2019 update: C++ will stay around for the next 10 years... (if not, I will correct this answer, when it will not be relevant any more....)

the reason companies works with COBOL today is b/c they already have millions of COBOL code written. if the could throw it - they will do it at once, on the other hand - companies work with C/C++ as part of their needs and new projects using this language b/c they can't / don't want to use java/c# any other framework based language - so COBOL is not the analogy here.

Like dsimcha said the D way is currently risky. Yet the language has a huge potential, it is low-level and i've experienced drastically better productivity with D (instead of C++). Perhaps what people feel with dynamic languages.

Go is so much blog-marketed it seems like a joke to me.
Dispatching an interface method is not trivial, and actually slower than dispatching a regular single-inheritance method.

If you'd have a huge codebase the decision is of course more difficult, I would advise only to switch for new projects, not for existing ones.

I wouldn't concentrate on a language but more on the libraries surrounding it. C++ in combination with the boost libraries are an excellent choice. People who develop in C++ tend to have a better understanding of computing, I myself started of with Java which made my life easier by hiding a lot of fundamental stuff, which is good, however I only really started to understand programming once I learned C/C++ (pointers etc).

I do recognise that C++ can be hard (e.g. memory management) so I think it's good to have a 'add on' language where performance is not essential and readability (==maintainability) scores high: I recommend Python for this.

There are countless machines running C++ software, I don't see them shutting down all at once. If C++ will go in the way of COBOL there will be a huge market for application migration. There will be specialized tools developed to translate C++ applications to the popular language of the time (Z++ ???).

So I guess the best advice is to cross that bridge when you come to it.

Check out Intel® Cilk++ Software Development Kit if you want to spark your interest in C++/Multi-Core development. I don't see C or C++ going away anytime soon either.

Comparing C* to Cobol is questionable

Comparing C* to Cobol may lead to the wrong conclusion. C was perfect for its day, a huge leap forward on its introduction, and it still gets the job done today.

I would sum up Cobol on my most charitable day with "nice try".

C and C++ will survive for a long time because they fit the bill well as implementation languages. This won't ever really change.

Also, consider that the main negative issue with C/C++ is the lack of memory safety. This tends to be less and less of a problem as codes mature. This means there will not be a serious reason to replace the old codes.

I expect that software systems will grow outwards from C. Look at the hierarchy today:

• application written in a framework such as Rails
• application back-end written in Ruby, PHP, Python, C#, whatever
• Ruby, PHP, Python, or C# run-time implementation (written in C*)
• OS kernel (written in C89)

I don't think the old layers will vanish, and I think legacy higher layers written in C and C++ will simply be supported that way for an indefinite period of time, eventually being phased out for their replacements written in Ruby, Python, C#, or a future development.

We have no idea if Go will find acceptance. Just being by Google is probably not going to be enough.

D? Well, some nice things are being said about it but it won't be taking off either. No user base to speak of. D is #20 in popularity on the <a href="http://www.tiobe.com/index.php/content/paperinfo/tpci/index.html">TIOBE Index</a>, and dropping fast.

You may say that a language's popularity has little to do with how well it's suited for your company's work. But it has a lot to do with how easy it will be to find people qualified to program in it.

Java is on top and I would be surprised if it went far away in the next 20 years. It's not considered a systems programming language but performs well enough that there are few tasks you'd do in C++ that you couldn't in Java. Certainly these days nobody is willing to task human programmers with the job done (flawlessly and often more effectively) by the garbage collector. I for one considered Java a significant step up from C++ in terms of programming effectivity.

I'm quite impressed by Ruby. It's an elegant, expressive language: You can accomplish a lot with not too much code, yet that code is still mostly legible. One of Ruby's main principles is to be consistent and not hold surprises for the developer. This is an extremely good idea, IMO, and boosts productivity. At the time of the big Rails hype (which may still be ongoing), I made a wide berth around Ruby because its reference implementation is abysmally slow. However, the JRuby folks at Sun have made it blazingly fast on a JVM, so now it's definitely worth some consideration. Ruby provides closures and a good handful of functional programming capabilities (see below for why this important), though it's not really considered a FP language. TIOBE index: 10 and rising.

Something to consider for the future is the fact that CPU makers have run up against a performance limit imposed by physics. No longer is there a 30% faster CPU available every Christmas, as it was in the past. So now to get more performance you need more cores. Software development will need all the help it can get in supporting multi-core concurrent programming. C++ leaves you mostly alone with this, and Java's solutions are horrible by modern standards.

In view of this, there's a certain trend toward functional programming (which eliminates much of the hassle associated with concurrency) as well as languages with better concurrency support. Erlang was written specifically for this and for the ability to swap code in a running program (Ericsson wanted incredible uptimes). Scala is similar to Java but with much stronger support for functional programming and concurrency. Clojure, ditto, but it's a Lisp and it's not even in the top 50 (yet!!).

Scala was developed academics, and shows it: It's sophisticated and downright pedantic about data types; it tries to be the Swiss Army Knife of programming languages. I believe a lot of medium-smart programmers will have trouble getting a grip on Scala. Ruby is less FP and doesn't do so much about concurrency, but it's pragmatic, and fun and easy to get stuff done in. Also, running on the JVM, there is an enormous amount of code readily available in Java libraries, which Ruby can interface with. So:

My bet would be on Ruby, with an outside chance on Scala. But there are plenty of alternatives!

Java. For most low level things Java is fine these days. Why go with a partial solution to C/C++ such as D or Go when you can have something as safe and easy to develop with as Java? If you are looking for a real time solution, D and Go are definitely not it, not to mention they are probably even less supported than Java.

Java is now a system programming language. I don't see how you can consider anything with unsafe constructs such as pointers "next gen". The only reason those insecure constructs ever existed is because it was the pragmatic approach to building a turing complete language. There was no concern of representing the memory in discrete objects, because they just wanted to build something that worked. There are already hard and soft realtime applications in Java, a variety of hardware bytecode processors, and over 2 billion mobile devices running Java. At most all you would have to do is add some constructs for interoperability with devices, which wouldn't be that much code; even in C/C++ you'd still have to add these constructs...

What are you programming? 8-bit microcontrollers with 1KB ram? In that case, it would be pointless to use anything other than the assembler for that platform...