| ||174||Data Parallel Haskell has seen few user-visible changes since the last report. Nevertheless, Roman Leshchinskiy has been busy improving many of the fundamental building blocks behind the scenes. These changes were necessary as DPH is able to generate very fast parallel code for simple examples, but the optimisation infrastructure has been too fragile. Small changes to other parts of GHC (most notably, the Simplifier) or to the DPH libraries could lead to dramatic performance regressions. Over the last few months, Roman has been working on making the system more robust, while Simon PJ improved and extended parts of GHC's existing optimisation infrastructure (such as the Inliner and other aspects of the Simplifier) to support Roman's efforts. As a first consequence of these efforts, the divide-and-conquer quickhull benchmark (computing a convex hull) is now significantly faster than the corresponding list-based implementation [!QuickHull]. This is an important milestone as quickhull uses dynamically nested parallelism whose depth is not statically bound.