We present a unified environment for running declarative
specifications in the context of an imperative object-oriented
programming language. Specifications are Alloy-like, written in
first-order relational logic with transitive closure, and the
imperative language is Java. By being able to mix imperative code with
executable declarative specifications, the user can easily express
constraint problems in place, i.e., in terms of the existing data
structures and objects on the heap. After a solution is found, the
heap is updated to reflect the solution, so the user can continue to
manipulate the pro- gram heap in the usual imperative way. We show
that this approach is not only convenient, but, for certain problems
can also outperform a standard imperative implementation.  We also
present an optimization technique that allowed us to run our tool on
heaps with almost 2000 objects.