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<p class=MsoNormal><span style='font-family:"Segoe UI","sans-serif"'>Hello
IronPython Community,<br>
<br>
We have just released IronPython 2.0 Alpha 1. IronPython 2.0 will be the first
release of IronPython built upon a common dynamic language runtime (DLR) as
well as targeting version 2.5 of Python. These release notes list what is new
in IronPython 2.0, a brief overview of the DLR, and what to expect from the 2.0
release.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Segoe UI","sans-serif"'><br>
One major focus during this release will be further improving our conformance
with CPython. We’ve already made several improvements, for example one is
that our type system no longer contains a hierarchy of types: now type(type) is
type. We have also fixed a number of issues related to various statements such
as imports and function definitions inside of exec or eval. There have also
been a number of other small issues fixed that our users reported to us.<br>
<br>
IronPython 2.0 will also be the first major release to support 2.5 out of the
box. In IronPython 1.x, and in this initial alpha release, users must enable
this with a command line switch. During the 2.0 release cycle we will flush out
the remaining 2.5 features and permanently enable this option. We will also
start looking at supporting v2.6 features via command line switch and start
some experimentation around the 3.0 features. In particular, we are excited
about looking at the new bytes and string types as well as formatting options
that we believe will fit nicely with .NET.<br>
<br>
IronPython 2.0 is also the first release built upon the Dynamic Language
Runtime: a shared runtime for dynamic languages on .NET. The DLR both reduces
the amount of work to create new dynamic languages on .NET enables rich
interoperability between dynamic languages, and provides a shared module for
consuming those languages from applications. We are particularly excited about
the ability to share code across dynamic languages enabling users to share
libraries without worrying the particular language in which the library is
written. Over time, the DLR will expand and improve bringing language
developers more benefits from this shared infrastructure. We also look forward
to seeing a new era of programmable apps that can support a wide range of
options for end-users.<br>
<br>
When we started working on the DLR we initially used the IronPython v1.0 code
base. From there we extracted the core concepts that were common to dynamic
languages, generalized the concepts that were specific to Python, expanded the
framework to provide rich support for other dynamic languages, and exposed all
of the languages via a common interface. Starting with IronPython 1.0 was an
obvious choice because it had already captured many of the best practices for
building dynamic languages on .NET and had done a great job leveraging many of
the underlying features of .NET. In IronPython 2.0 all of these best practices
are expanded and implemented with an eye on maximizing forward compatibility
with new features in .NET v3.5 such as LINQ and extension methods. Moreover,
the DLR exposes this functionality to the language implementer via a small set
of core concepts that all dynamic language implementations can share.<br>
<br>
One additional change in this release is that we’re moving to use the
Microsoft Permissive License for IronPython 2.0. Our original release of
IronPython predated the Microsoft Permissive License, and so we created a
custom license specifically for Iron Python. After releasing Iron Python, we
created new Microsoft Shared Source licenses, including the Microsoft
Permissive License, to facilitate and standardize source code licensing for
appropriate Microsoft projects. We believe our users appreciate consistency in
licensing from Microsoft. Therefore, because we are now using the more modern
Microsoft Permissive License where appropriate for similar current source code
releases, we feel we should offer IronPython under the Microsoft Permissive
License as well.<br>
<br>
Note because this is an alpha release there is also some missing functionality
that was formerly present in v1.0. This includes CodeDom support, the static
compiler that produced .NET assemblies, support for creating strongly typed
delegates to script code, as well as a drastically changed hosting API. We will
be bringing this functionality back to future releases in the IronPython 2.0
series as well many other improvements.<br>
You can download IronPython v2.0 at: <a
href="http://www.codeplex.com/IronPython/Release/ProjectReleases.aspx?ReleaseId=438">2.0
Alpha</a><br>
<br>
If you’d like more details about the DLR, Jim will be using his blog to
post design notes as they are written over the next couple of weeks – <a
href="http://blogs.msdn.com/hugunin">http://blogs.msdn.com/hugunin</a>.<o:p></o:p></span></p>
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