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SBT is required for building, and depedency 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#installhtml#installing-sbt
Daffodil is written in Scala 2.9.2, which also must be installed in order to run Daffodil.
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