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SBT is required for building, and depedency dependency management. See the README and BUILD files in the root of your local clone of the git repository. In short, you need to download and put the correct SBT Launcher in your path. Daffodil is currently using version 0.12.1 of SBT. SBT is available here: http://www.scala-sbt.org/release/docs/Getting-Started/Setup.html#installing-sbt
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Next you need to configure daffodil to use the version of the Scala compiler downloaded by Ivy. This will be a local setting and not the global FCS setting so each module has to be updated individually. Right-click on daffocildaffodil-core and select "Open Module Settings". Then for each module, open up it's children, select "Scala" from the list of children and click the "Use ordinary compiler" for the Compiler Installation. This should default to scala-2.9.1 which is the version downloaded by Ivy and configured in the Intellij project.
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