Ceylon 1.3.1 is now available

Ceylon 1.3.1 is a significant minor release of the Ceylon language, with over 140 issues closed. This is the first release of Ceylon which supports interoperation with Java 8 lambdas and streams, with RxJava, and with Spring Boot. This release also introduces support for static members.

This release of Ceylon has been tested with a wide variety of Java libraries and frameworks, including:

Example code demonstrating the use of these frameworks is available.

Compared to previous releases of Ceylon, the use of Java frameworks based on reflection is now much more transparent, and integration with multi-module Maven-based platforms and frameworks is now much easier to configure.

The Ceylon tour has been extensively updated, especially the sections addressing interoperation with native Java and JavaScript, and with the module system.


Enhancements to the language and command-line distribution include:

  • static members in Ceylon classes
  • interoperation with Java 8 lambdas—ability to pass Ceylon functions to Java SAM types
  • local import statements
  • support for spread operators * and *. with java.lang.Iterable and Java arrays
  • literal tuples in cases of a switch
  • small Characters
  • new Maven interop mode --fully-export-maven-dependencies for projects depending on multi-module platforms like Spring Boot
  • support for POM-only Maven artifacts
  • new Java EE-friendly compiler mode, making it easy to use Java frameworks that depend on reflective direct access to fields
  • ability to pass Ceylon metamodel to Java methods accepting java.lang.Class
  • ability to pass Ceylon strings to Java methods accepting java.lang.CharSequence
  • improved treatment of null values originating in calls to native Java
  • several bugfixes to relating to interop with overloaded Java methods
  • new command line options: --java, --incremental, and --include-dependencies

Naturally, the release incorporates many more bugfixes and minor enhancements.

IDE Changes

Ceylon IDE 1.3.1 for IntelliJ and Eclipse resolves more than 110 issues, and adds support for running and debugging Ceylon programs on WildFly Swarm.


SDK Changes

Exactly 15 issues affecting the Ceylon SDK have been fixed, and the new platform modules ceylon.interop.spring and ceylon.interop.persistencewere introduced. New 1.3.1 releases of the platform modules are available in Herd.


  • For the JVM, this release is backwards-compatible with all previous releases of Ceylon since 1.2.0.

  • For JavaScript, this release is backwards-compatible only with the previous two releases (1.2.2 and 1.3.0).

Ceylon 1.3.1 is backward-compatible with Ceylon 1.3.0, and so it’s not necessary to recompile or change dependencies. However, upgrading to version 1.3.1 of any Ceylon platform module is recommended.

About Ceylon

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 IDE supporting both IntelliJ IDEA and the Eclipse platform.

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.

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, a test runner, a WAR archive packager, a “fat” JAR packager, 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, which also supports interoperation with OSGi, Jigsaw, Maven, and npm, and
  • the language module, our minimal, cross-platform, foundation-level API.

Available separately:


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,
  • 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.


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

You can follow @ceylonlang on Twitter.

Source code

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

Information about Ceylon’s open source licenses is available here.


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

Reference: Ceylon 1.3.1 is now available from our JCG partner Gavin King at the Ceylon Team blog blog.
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