Neptune is a build tool with similar scope as Ant. There are two major differences between Neptune and Ant:

1. Neptune is based on command pattern. The Command interface allows an Object as return value, while Ant Task has no return value. The only way in Ant for a Task to communicate with other Task or the execution engine is through system property values, which are essentially string-only global variables.

2. Neptune is currently supported by the Jaskell scripting language, which allows flexible combinations of Neptune Command objects. Function, higher-order funciton, monadic combinators can all be used to reuse code and combine Command objects. While Ant is based on XML, which is not an ideal language for expressing logic.

Neptune currently delegates to Ant for most atomic tasks. All Ant core and optional tasks are adapted as Neptune commands with exactly the same set of properties and sub-elements as in Ant.

This means knowledge of Ant tasks can be reused in Neptune. All one has to do in order to call an Ant task in Neptune is:
1. check out the Ant manual for the supported properties and sub-elements.
2. call the ant task from within neptune with a different syntax. (not xml, but a neptune script)

A shell is provided to allow executing Neptune commands and Ant tasks interactively.

Please refer to http://jaskell.codehaus.org/Using+Neptune for details.