Ceylon 1.1.0 is now available

Ten whole months in the making, this is the biggest release of Ceylon so far! Ceylon 1.1.0 incorporates oodles of enhancements and bugfixes, with well over 1400 issues closed.

Ceylon is a modern, modular, statically typed programming language for the Java and JavaScript virtual machines. The language features a flexible and very readable syntax, a unique and uncommonly elegant static type system, a powerful module architecture, and excellent tooling, including an awesome Eclipse-based IDE.

Ceylon enables the development of cross-platform modules that execute portably in both virtual machine environments. Alternatively, a Ceylon module may target one or the other platform, in which case it may interoperate with native code written for that platform.

For the end user, the most significant improvements in Ceylon 1.1 are:

  • performance enhancements, especially to compilation times in the IDE,
  • even smoother interoperation with Java overloading and Java generics,
  • out of the box support for deployment of Ceylon modules on OSGi containers,
  • enhancements to the Ceylon SDK, including the new platform modules ceylon.promise, ceylon.locale, and ceylon.logging, along with many improvements to ceylon.language, ceylon.collection, and ceylon.test,
  • many new features and improvements in Ceylon IDE, including
  • ceylon.formatter, a high-quality code formatter written in Ceylon,
  • support for command line tool plugins, including the new ceylon format and ceylon build plugins, and
  • integration with vert.x.

A longer list of changes may be found here.

In the box

This release includes:

  • a complete language specification that defines the syntax and semantics of Ceylon in language accessible to the professional developer,
  • a command line toolset including compilers for Java and JavaScript, a documentation compiler, and support for executing modular programs on the JVM and Node.js,
  • a powerful module architecture for code organization, dependency management, and module isolation at runtime,
  • the language module, our minimal, cross-platform foundation of the Ceylon SDK, and
  • a full-featured Eclipse-based integrated development environment.


Ceylon is a highly understandable object-oriented language with static typing. The language features:

  • an emphasis upon readability and a strong bias toward omission or elimination of potentially-harmful or potentially-ambiguous constructs and toward highly disciplined use of static types,
  • an extremely powerful and uncommonly elegant type system combining subtype and parametric polymorphism with:
    • first-class union and intersection types,
    • both declaration-site and use-site variance, and
    • the use of principal types for local type inference and flow-sensitive typing,
  • a unique treatment of function and tuple types, enabling powerful abstractions, along with the most elegant approach to null of any modern language,
  • first-class constructs for defining modules and dependencies between modules,
  • a very flexible syntax including comprehensions and support for expressing tree-like structures, and
  • fully-reified generic types, on both the JVM and JavaScript virtual machines, and a unique typesafe metamodel.

More information about these language features may be found in the feature list and quick introduction.

This release introduces the following new language features:

  • support for use-site variance, enabling complete interop with Java generics,
  • dynamic interfaces, providing a typesafe way to interoperate with dynamically typed native JavaScript code,
  • type inference for parameters of anonymous functions that occur in an argument list, and
  • a Byte class that is optimized by the compiler.

Language module

The language module was a major focus of attention in this release, with substantial performance improvements, API optimizations, and new features, including the addition of a raft of powerful operations for working with streams.

The language module now includes an API for deploying Ceylon modules programmatically from Java.

The language module is now considered stable, and no further breaking changes to its API are contemplated.

Command line tools

The ceylon command now supports a plugin architecture. For example, type:

ceylon plugin install ceylon.formatter/1.1.0

To install the ceylon format subcommand.


This release of the IDE features dramatic improvements to build performance, and introduces many new features, including:

  • a code formatter,
  • seven new refactorings and many improvements to existing refactorings,
  • many new quick fixes/assists,
  • IntelliJ-style "chain completion" and completion of toplevel functions applying to a value,
  • a rewritten Explorer view, with better presentation of modules and modular dependencies,
  • synchronization of all keyboard accelerators with JDT equivalents,
  • Quick Find References, Recently Edited Files, Format Block, Visualize Modular Dependencies, Open in Type Hierarchy View, Go to Refined Declaration, and much more.


The platform modules, recompiled for 1.1.0, are available in the shared community repository, Ceylon Herd.

This release introduces the following new platform modules:

  • ceylon.promise, cross-platform support for promises,
  • ceylon.locale, a cross-platform library for internationalization, and
  • ceylon.logging, a simple logging API.

In addition, there were many improvements to ceylon.collection, which is now considered stable, and to ceylon.test.

The Ceylon SDK is available from Ceylon Herd, the community module repository.

Vert.x integration

mod-lang-ceylon implements Ceylon 1.1 support for Vert.x 2.1.x, and may be downloaded here.


The Ceylon community site, http://ceylon-lang.org, includes documentation, and information about getting involved.

Source code

The source code for Ceylon, its specification, and its website is freely available from GitHub.


Bugs and suggestions may be reported in GitHub's issue tracker.


We're deeply indebted to the community volunteers who contributed a substantial part of the current Ceylon codebase, working in their own spare time. The following people have contributed to this release:

Gavin King, Stéphane Épardaud, Tako Schotanus, Emmanuel Bernard, Tom Bentley, Aleš Justin, David Festal, Max Rydahl Andersen, Mladen Turk, James Cobb, Tomáš Hradec, Ross Tate, Ivo Kasiuk, Enrique Zamudio, Roland Tepp, Diego Coronel, Daniel Rochetti, Loic Rouchon, Matej Lazar, Lucas Werkmeister, Akber Choudhry, Corbin Uselton, Julien Viet, Stephane Gallès, Paco Soberón, Renato Athaydes, Michael Musgrove, Flavio Oliveri, Michael Brackx, Brent Douglas, Lukas Eder, Markus Rydh, Julien Ponge, Pete Muir, Henning Burdack, Nicolas Leroux, Brett Cannon, Geoffrey De Smet, Guillaume Lours, Gunnar Morling, Jeff Parsons, Jesse Sightler, Oleg Kulikov, Raimund Klein, Sergej Koščejev, Chris Marshall, Simon Thum, Maia Kozheva, Shelby, Aslak Knutsen, Fabien Meurisse, Sjur Bakka, Xavier Coulon, Ari Kast, Dan Allen, Deniz Türkoglu, F. Meurisse, Jean-Charles Roger, Johannes Lehmann, Alexander Altman, allentc, Nikolay Tsankov, Chris Horne, gabriel-mirea, Georg Ragaller, Griffin DeJohn, Harald Wellmann, klinger, Luke, Oliver Gondža, Stephen Crawley.