Scala is a strongly typed language that is highly compatible with Java, but improves on it in several respects. From the GWT developer's perspective:
We want to be able to move or copy Scala server-side code to the client. Since GWT will only compile Java at present, only Java code can be reused in this way.
Writing GWT code typically involves a lot of composition. Scala traits would really help declutter. Scala has less boilerplate than Java, so GWT code written in Scala should be shorter, more expressive, and more maintainable.
Scala code cannot be transformed to strict Java. It is not possible with present tools to produce bytecode with Scala, decompile it to valid Java, and put the resulting source into GWT, or even to produce valid Java directly from Scala, although the experimental java-src backend gets reasonably close. Together, these issues make the problem set a little more challenging.
For more discussion of this issue, see this October 2009 thread on google-web-toolkit-contributors , which spawned this project.
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