Another example combining JDeferred with Groovy

jdeferred_example_2.groovy

@Grab('org.jdeferred:jdeferred-core:1.2.4')
import org.jdeferred.*
import org.jdeferred.impl.*

def d = new DeferredObject()
def p = d.promise()

// gotta be explicit and can't use Groovy closures:
// DoneCallback / DoneFilter / DonePite are ambiguous
// in terms of signature, for SAM type coercion
def filtered = p.then(new DoneFilter<Integer, Integer>() {
    Integer filterDone(Integer result) {
        result * 10
    }
}).done { result ->
    // result would be original * 10
    assert result == 30
}

d.resolve(3)