Scala 2.8.0 RC6
After a few more fixes, a new release candidate is ready! The new Scala
2.8.0 RC6 is available for testing: you can find it on our Download Page
The Scala 2.8.0 codebase includes a huge number of bug fixes with respect
to 2.7.7, and an impressive amount of new features.
These are the changes between 2.8.0.RC5 and 2.8.0.RC6:
* Fixed #3563, #3550, #3125, #3568, #3420, #3558
* Improved fix to #3174 and #3560
* Fixed pattern matcher issue #3578 (reopened #2800, #3050)
* Fixed a classpath-related bug in scripts
* Removed problematic integration of placeholder syntax and
The Scala 2.8.0 RC6 distribution
This Release Candidate is made available for testing purposes only,
and is not intended for production environments. We will wait a
minimum of two weeks before issuing a final release, in order to
allow developers and testers to send us their feedback.
What is new?
The new Scala 2.8 codebase includes the following new fixes and features:
- Redesigned collection library
The collection library has undergone a complete overhaul for Scala
2.8, offering a more coherent and efficient design, while
maintaining virtually complete compatibility with existing sources.
Detailed information at: http://www.scala-lang.org/sid/3
- New array implementation, manifests for polymorphic arrays
Handling of arrays has been simplified and optimized in Scala 2.8.
The previous compiler magic has been replaced by a more systematic
and predictable implementation in terms of implicit conversions.
Full details at: http://www.scala-lang.org/sid/7
- Type specialization
Scala 2.8 adds specialized type parameters, which enable the
compiler to generate transparently multiple versions of a given
definition, and to use the most specific version whenever the static
type information at a call site allows it. Details at:
- Named and default arguments
Named arguments improve the readability of method calls with many
arguments. Default arguments reduce code duplication, and enable
"copy" methods for case classes, useful to generate quickly modified
copies of case classes. A complete description at:
- Package objects
Packages can now contain besides classes and objects also methods,
fields or type aliases. These are added to a package by declaring a
package object. More capabilities might be added to package objects
in subsequent releases.
- Beefed up Scala Swing libraries, better documentation
Components publish key events, input events can be consumed,
refactored window subhierarchy, additional demos, Swing listeners
are installed lazily, more complete component caching, minor
refactorings, bugfixes, more Scaladocs. Design document at:
- Revamped REPL
Many bugfixes. Tab-completion for all packages on the classpath, as
well as object and instance methods and fields, including type
aliases and package objects. Searchable history, integrated shell
access, and a power mode which offers direct access to compiler
- Implicits changes
We have refined the implicit resolution process so that resolution
is now able to determine type variables.
- Improved equality
Equality across numeric types is to be consistent across all the
primitives types, while also adhering to the equals/hashCode
contract. Numeric comparisons will have the same results as they
would between Java primitives. This is currently still being
- Packrat parser combinators
With support for packrat parsing, parser combinators are now able to
handle left-recursive grammars and will show improved performance
for ambiguous productions.
- Improved XML library
- Type constructor inference
Type inference has been extended to deal with type constructors,
so that, in certain cases, you can omit type parameter lists that
contain higher-kinded types (aka type constructors, e.g., List).
- Improved Annotations
Scala 2.8 adds support for nested java annotations. For annotations
on fields, it is now possible to specify which synthetic members
(getter / setter) will have the annotation. Documentation about
Scala annotations can be found at: http://www.scala-lang.org/sid/5
- Enhanced actors
New Reactors provide more lightweight, purely event-based actors
with optional, implicit sender identification. Support for actors
with daemon-style semantics was added. Actors can be configured to
use the efficient JSR166y fork/join pool, resulting in significant
performance improvements on 1.6 JVMs. Schedulers are now pluggable
and easier to customize.
- Support for continuations
Continuations are supported by a compiler plugin, which is now
supported as part of the main distribution.
- New presentation compiler
This new infrastructure, within the Scala compiler, enables IDEs to
hook into the compiler to find efficiently information about the
structure of the program under editing. This new code offers a
better platform for the development of IDE plugins.
- New build manager
The new feature used by for example Eclipse to detect intelligently
changes in the files and compile only necessary Scala sources,
instead of performing clean build on whole projects. This technique
enables to significantly reduce the compilation time on bigger
- Speed improvements
The compiler now runs as optimised code. In addition, a number of
improvements and fine-tunings have further improved the compiler
speed up to 50%.
- Scala 2.8 includes a huge number of bug fixes; the main ones are
listed at: http://www.scala-lang.org/node/299
- Scaladoc 2
A new look-and-feel, automatic comments expansion and wiki-like
syntax, as well as compile-time error checking. Read more about
changes on the Scaladoc 2 mini-site at
- Sbaz 2
Sbaz includes many bug fixes and enhancements. It now gives better
feedback to the user during lengthy downloads and while diagnosing
dependency audits, which in turn have been re-factored and enhanced.
Sbaz should work properly on Windows using either cmd or cygwin, and
is now capable of reliably updating itself. Support for pack200 has
been added, in some cases reducing file sizes up to 70%.
A new Scalap, contributed by the community, is included. The new
Scalap is aware of package objects and can decompile them by using
- Scala IDE for Eclipse
The IDE has been extensively reworked with much functionality moved
into the Scala compiler where it can be better maintained and reused
by non-Eclipse IDEs and other tools. The integration with Eclipse's
JDT has been deepened, and much previously Scala-specific behaviour
and functionality is now provided directly by the JDT leading to
across the board improvements.
The Scala IDE for Eclipse is now hosted at Assembla, at:
http://www.scala-ide.org. You can obtain it from its download
page at http://download.scala-ide.org.
Acknowledgments and Thanks
Many members of the Scala community have helped us by fixing or
reporting bugs, contributing new code and tools (including some of
those listed above), and addressing user questions on the mailing
lists: their contributions help shaping the future of Scala day by
- We would like to thank:
Paul Phillips, Miles Sabin, Ilya Sergey, Caoyuan Deng, James Matlik,
Frank Teubler, Kevin Wright, Manohar Jonnalagedda, Pedro Furlanetto,
Johannes Rudolph, Jason Zaugg, Seth Tisue, Ismael Juma, Mark Harrah,
Colin Howe, Mirko Stocker, Spiros Tzavellas, Matt Russell, David
Taylor, and all the other frequent contributors to our mailing lists,
too many to list here. Thank you all!
The Scala Team at EPFL
Martin Odersky, Lukas Rytz, Hubert Plociniczak, Iulian Dragos,
Gilles Dubochet, Philipp Haller, Aleksandar Prokopec, Antonio Cunei,
Tiark Rompf, Miguel Garcia, Donna Malayeri, Phil Bagwell, Adriaan
Moors, Ingo Maier.