Hello IronPython Community,


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.


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.

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.

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.

When we started working on the DLR we initially used the IronPython
v1.0code 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.

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.

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.
You can download IronPython v2.0 at: 2.0
Alpha<http://www.codeplex.com/IronPython/Release/ProjectReleases.aspx?ReleaseId=438>

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 ¨C
http://blogs.msdn.com/hugunin.



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Learning English...
Thanks for your help.
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