When comparing Ceylon vs Earl Grey, the Slant community recommends Ceylon for most people. In the question“What are the best languages that compile to JavaScript? ” Ceylon is ranked 15th while Earl Grey is ranked 29th. 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 Powerful hygienic macros
Earl Grey's macro system allows for creating powerful control structures that look just like builtin ones. EG also supports macro libraries which allows developers to provide their macros/DSLs for others to use.
Pro Pattern matching
Pattern matching is an incredibly powerful tool that, once you've tried, you cannot live without. This is not your average hacked-together pattern matching but a complete and integral feature to the language.
Pro ECMAScript 6 Asynchrony
Earl Grey provides Promises based on ECMAScript version 6 and as many NPM libraries already implement. Earl Grey also provides a promisify
function that converts old-fashioned callback-style asynchrony to promises.
Pro Fully compatible with Node.js ecosystem
Anything available on NPM can be used just as easily with Earl Grey. In fact, everything else can be used too! Earl Grey has interfaces to Browserify, Webpack, and even experimental support for SystemJS. Earl Grey can even be used to generate npm packages that any node-compatible language can use!
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 Not true static typing
EG gives you the tools to implement your own type-checking inside of argument lists and elsewhere but there's no analysis done at compile-time like other compile-to-js languages.
Con Unfamiliar syntax
While the language shares a lot of DNA with Python, there are still many new (and interesting) features/sugar that may take some time to get used to.
