When comparing Ceylon vs C#, the Slant community recommends Ceylon for most people. In the question“What are the best languages for learning functional programming?” Ceylon is ranked 12th while C# is ranked 25th. The most important reason people chose Ceylon is:
It has a Web IDE: http://try.ceylon-lang.org/ with impressive demos: http://try.ceylon-lang.org/?gist=bd41b47f325b6d32514a so you can try it without installing anything, and see the JS generation / interop in action.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Try it out in the browser
It has a Web IDE: http://try.ceylon-lang.org/ with impressive demos: http://try.ceylon-lang.org/?gist=bd41b47f325b6d32514a so you can try it without installing anything, and see the JS generation / interop in action.
Pro Strong static typing, null safe and flexible, almost dynamic type system
The compiler prevents you from using a potentially null variable, unless you check it is not null. Ie. it forces you to check a potentially null value before using it.
The type system is strict, but flexible, allowing union and intersection of types, covariant and contravariant types, reified types, etc.
Type inference and union types allows a dynamic programming style, close of JS spirit.
Pro Designed from the start to generate JavaScript
It brings type safety to JS, allowing to define interfaces to existing JS APIs, yet using the dynamic
keyword for flexible calls in the JS ecosystem.
Pro Excellent IDE support
Ceylon has reified generics, so it doesn't loose the type of collections at runtime. This makes autocompletion, debugging, etc. first-class. The Eclipse plugin makes it a full-fledged Ceylon IDE, and an IntelliJ IDEA plugin is in the works.
Pro Great tutorial
Gavin King, main author of the language, has a great, clear technical writing style, making understandable difficult concepts like variance or sound type system.
Pro Excellent documentation
The language specification is very complete and up to date; also, the language module is very well documented.
Pro Javascript interoperability
Ceylon has special language-level support for interoperation with dynamically typed languages like JavaScript, and its module system even interoperates with npm.
Pro Easy to learn even if you don't have prior programming experience
Ceylon is indeed fairly easy and readable. Of course those ones who know OOP and a bit of functional programming concepts will feel almost at home right from the start.
Pro Generate HTML
HTML generation is supported right in the SDK.
Pro Same code in backend and frontend
If you don't use platform-specific features, you can reuse the same code in your backend server (be it in Java or JavaScript) and in your client-side browser code, for example for storing data, validating input etc.
Pro Versatile
.NET offers rich functionality.
Pro Visual Studio
The Visual Studio IDE offers one of the best development environments. The Community Edition and Visual Studio Code can be used for free.
Pro Forms
Can be designed visually with the Visual Studio designer for traditional Windows forms, WPF, or Web forms.
Pro 3rd Party support
Lot's of tools and libraries available.
Pro Can be used in a variety of fields
With Xamarin for Mobile (ios, android),
with .net core asp for server (linux, windows),
with .net core for desktop (windows, mac),
with mono for desktop (windows, linux),
with blazor for web client with webassembly.
However, it is not considered top for any of those categories, but it is top choice for Windows desktop with .net framework and top choice for Unity.
.net 5 will unify frameworks similar to JVM (just one).
Pro Cross-Platform
Runs on Linux, Mac, and Windows.
Pro Supported By Microsoft
Constant updates and bug fixes to many popular frameworks, as well as great first-party support from Microsoft. This can be a con as well in certain circumstances.
Pro It is a C like language
Being a C like language counts in favor for it as a general purpose programming language, given the ease of using existing skills to pick up this language easily.
There are other superior languages that could be used as a general purpose, such as: F#, Haskell, but the complexity of those languages, being functional, make them strange to the usual C Syntax.
C# is better than C whenever garbage collection, Objects, classes, data access, are needed. But C is going to be the choice when hardware access and performance are paramount.
Cons
Con Lack of physical or electronic books
We should hope Red Hat or anyone interested would take the time and write one. That would strengthen the maturity of the language, but Ceylon is rapidly developing which can make the author's efforts futile because his or hers work will become obsolete soon.
The second hindrance is, of course, popularity of the language which can't give much to the pockets of the author (however, Dart's unpopularity at start didn't prevent it to have a lot of printed material, but that's Google's child, we know).
Con Currently has large runtime
Ceylon 1.2 needs a language runtime of 1.55 MiB, and the Collection library adds another 370 KiB. That's a lot for the Web...
Now, this has to be put in perspective: if you use Ceylon to make a web application, these files will be loaded once, then cached by the browser (that's not casual browsing).
Moreover, most servers compress such resource, and the numbers become respectively 234 KiB and 54 KiB, which is more reasonable...
Con Learning curve
For a beginner the .NET framework can be daunting, the rich functionality means that things often can be done in several ways.
Con Very large runtime
Cannot be used for embedded programming.
Con Microsoft will mess up with the Visual studio installation
And all of a sudden you'll need to reinstall the entire thing just because it stopped working.
Microsoft assumes that every workstation is connected to the Internet then it is always pushing updates.
Con .NET is a mess
Troublesome in regards to being Microsoft centric, updates, security, excessively large, cross-platform issues, etc...
Con Windows OS centric
Not very good at being a cross-platform programming language.
Con Strictly object oriented
Con Owned by Microsoft
And like always, Microsoft is to be avoided, no exceptions.
