“C#, it’s just not portable”

You can use C# everywhere, but in practice it just seems like a huge effort to avoid learning a new language to me.

I have nothing against the language (writing C# is half of my day job), but all of these bridges are second-class citizens and built and maintained at the mercy of third parties just to interface with your target platform. Apple will never release updates for MonoMac or MonoTouch. Google isn't going to release C# Android SDKs or documentation. Mono for Linux always trails the Windows version and has significant community resistance, and Microsoft isn't going to integrate and maintain these bridges.

You're also always losing something in the translation too, be it idiomatic style of the target API or C#, or being totally cut off from new native features, or severely restricting what community support or documentation is available to you. Any way you cut it, it's a second class experience. Worse, some of the bridges aren't free. You get to pay $400 for the privilege of not learning a little bit of Java or ObjC to get MonoTouch for Android or iOS.

C# is good, but it's not so good that I refuse to learn other tools.

Just like most languages, you can take some subset of C# and run it in many places. And, like most languages, there is some corner of the language that doesn't work on one platform or another. And most importantly, just like most languages, you end up depending on various libraries which may or may not be tied to hardware which makes significant parts of non-trivial applications non-portable.

People don't make games in C# because it's C#. They make games using C# and XNA, or Unity, or some other framework. They don't make web apps in C#, but rather in (whatever flavor of) ASP.NET. And it turns out that these frameworks are the important bits.

So when you choose to write something in C#, you are probably going to be choosing a framework that ties you down to a platform, and that's where the cross-platform nature of the language kind of becomes irrelevant.

That's my experience, at least.

If Clojure takes off on other runtimes, it will have this issue too. The JVM is it's "home" platform, and most Clojure software depends on JVM libraries, like how the vast majority of the C# software written thus far depends on Microsoft (and therefore Windows) libraries.

C# is a good production language. It lets twiddle you your bits almost as well as C when you need to, provides a decent OO model, and has been piling on more functional and dynamic features as the years go by. However, as someone who has had to port a .Net C# app from windows to Linux, I can witness with sincerity that C# is NOT very portable.

First of all, a lot of the C# APIs are written with windows in mind. An example is system mutexes. These just don't exist on Linux, and the mono implementation to emulate them is very buggy. Another example is the process counter API. Although much of this same information is available on Linux via the Proc table, Mono provides no equivalent API because it would be a lot of work to make one that works on all the Unix variants. There are many such examples of C#'s windows-centric API not being ported well in Mono.

A bigger problem with Mono is that it just wasn't stable for us. The more standard library features we used, the more it would core dump on Linux even though it would never crash on windows. We ended up re-implementing a lot of functionality available in the standard library ourselves before the program stabilized on mono, which further incriminates the Mono stack. As a final note, we tried multiple versions of Mono, including 2.4, 2.6, and 2.10, and none of them worked well for us.

If you want to write a fairly performant cross-platform app, the JVM is still a much better place to play in right now than .Net, even though I like C# the language a lot more than I do Java. You can also go the route of combining your favorite scripting language with C for the CPU-intensive parts.

These days it seems like much of a language's benefit to developers comes from its libraries rather than from the elegance of its syntax or the ease of implementing an algorithm. The big question is, how much of the "standard" libraries are supported on these devices? I remember writing a C# application using Winforms back mid-last-decade and assuming that portability would be a cinch...right up until I realized that Winforms weren't supported by Mono yet and I was supposed to use Glade# or some such nonsense. C#'s mindshare mostly comes from Windows GUI developers, and telling these folks that they can use their pet language only if they relearn all the libraries isn't going to be much of a win, I don't think.

You could make the same argument about C, which exists on much more platforms than C#.

But writing in C does not make a program portable. Neither does writing it in C#.

So yes, C# compiler might be portable, but programs written in C# are not.

So yes, C# compiler might be portable, but C# programs are not.

C# as a system language running on Mono is actually usable. But the thing is, I've never seen an IDE worse than MonoDevelop. Writing C# without Visual Studio, a large part of the benefit of the language just disappears.

I would only use C# for window jobs, although I sincerely think it's a beautiful language.

I am currently writing an "enterprise" style application and backend framework (WCF, Fluent NHibernate, Castle, json-emitting webservices, etc) based on C# and Mono. I'd like to hear more stories of others doing the same. Mono has all the functionality I need, the only possible worry that I have is that of the default GC (and I don't know if the newer GC is stable enough).

Is anybody using Mono on Linux for ASP.NET MVC3 apps in production?

If so, is it stable, fast?

I wonder how it compares speed and stability wise to the Java Play Framework.

I am currently using Play (and it's great!) but I much prefer C# as a language to Java ...

Interesting. I always thought the Vita was running Android since it supports Android apps.

I feel like there is too much attention paid these days to who badmouthed your precious programming language, or whether your language has the appropriate amount of respect, or whatever. I'm a C# dev, sometimes. People have been hating on it (and its devs) for years, but it just doesn't matter. Get over it and use whatever language or other dev tool you want.

You might be able to write C# and target different platforms, but I've yet to be convinced that a codebase can be shared across platforms as easily as some other languages/platforms.