Ceylon M4 and Ceylon IDE M4 released!

Ceylon M4 "Analytical Engine" is now available for download, along with a simultaneous compatible release of Ceylon IDE. The compiler now implements almost all of the language specification, for both Java and JavaScript virtual machines as execution environments. New Ceylon platform modules are available in Ceylon Herd, the community module repository.

You can download the Ceylon command line distribution here:


Or you can install Ceylon IDE from Eclipse Marketplace or from our Eclipse update site.

Ceylon M4 and Ceylon IDE M4 require Java 7.

The Ceylon team hopes to release Ceylon 1.0 beta in January.

Language features

M4 is an almost-complete implementation of the Ceylon language, including the following new features compared to M3:

The following language features are not yet supported in M4:

  • reified generics
  • user-defined annotations, interceptors, and the type safe metamodel
  • serialization

This page provides a quick introduction to the language. The draft language specification is the complete definition.

Ceylon IDE

Ceylon IDE is a complete development environment for Ceylon, based on the Eclipse platform. This release of Ceylon IDE introduces:

  • support for JavaScript compilation and execution,
  • module import completion,
  • the brand new Ceylon Repository Explorer view,
  • support for Maven repositories, and
  • more than 30 other improvements and bug fixes.

Ceylon IDE M4 requires Java 7. Users of Ceylon IDE on Mac OS should install Eclipse Juno. Users on other platforms may run Ceylon IDE in either Eclipse Indigo or Eclipse Juno on Java 7. Ceylon IDE will not work if Eclipse is run on Java 6.

Compilation and execution on the JVM and JavaScript VMs

The Ceylon command-line tools and IDE both support compilation to either or both of the JVM or JavaScript.

Ceylon programs compiled to JavaScript execute on standard JavaScript virtual machines. The Ceylon command line distribution and IDE include a launcher for running Ceylon programs on Node.js.

Interoperation with Java

Interoperation with Java code is robust and well-tested. As usual, this release fixes several bugs that affected Java interoperation in the previous release.

Contrary to previous releases, the JDK is no longer automatically imported, so you need to import the JDK using the modularised JDK module names as defined by Jigsaw (Java 9).

Platform modules

The following new platform modules are now available in Ceylon Herd:

  • ceylon.net provides URI and HTTP support
  • ceylon.io provides charset and socket (blocking and non-blocking) support
  • ceylon.json provides JSON parsing and serialization
  • ceylon.collection collection implementations organized into mutable array-based collections, mutable hashtable-based collections and immutable linked-list based collections

The language module, ceylon.language is included in the distribution.

Modularity and runtime

The toolset and runtime for Ceylon are based around .car module archives and module repositories. The runtime supports a modular, peer-to-peer class loading architecture, with full support for module versioning and multiple repositories, including support for local and remote module repositories, using the local file system, HTTP, WebDAV, or even Maven repositories for interoperation with Java.

The shared community repository, Ceylon Herd is now online:


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.


The Ceylon community site includes documentation, the current draft of the language specification, the roadmap, and information about getting involved.



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, Flavio Oliveri, Max Rydahl Andersen, Mladen Turk, James Cobb, Tomáš Hradec, Michael Brackx, Ross Tate, Ivo Kasiuk, Enrique Zamudio, Julien Ponge, Julien Viet, Pete Muir, 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, Paco Soberón, sjur, Xavier Coulon.